[doc] update section "Executable Image Format"

cleanups and add support for mif file type

docs/datasheet/software.adoc

@@ -163,10 +163,12 @@ Targets:
  gdb        - run GNU debugging session
  asm        - compile and generate <main.asm> assembly listing file for manual debugging
  elf        - compile and generate <main.elf> ELF file
- bin        - compile and generate <neorv32_raw_exe.bin> RAW executable file (binary file, no header)
- hex        - compile and generate <neorv32_raw_exe.hex> RAW executable file (hex char file, no header)
- coe        - compile and generate <neorv32_raw_exe.coe>> RAW executable file (COE file, no header)
- mem        - compile and generate <neorv32_raw_exe.mem>> RAW executable file (MEM file, no header)
+ exe        - compile and generate <neorv32_exe.bin> executable image file for upload via default bootloader (binary file)
+ bin        - compile and generate <neorv32_raw_exe.bin> RAW executable memory image (binary file)
+ hex        - compile and generate <neorv32_raw_exe.hex> RAW executable memory image (hex char file)
+ coe        - compile and generate <neorv32_raw_exe.coe> RAW executable memory image (COE file)
+ mem        - compile and generate <neorv32_raw_exe.mem> RAW executable memory image (MEM file)
+ mif        - compile and generate <neorv32_raw_exe.mif> RAW executable memory image (MIF file)
  image      - compile and generate VHDL IMEM boot image (for application, no header) in local folder
  install    - compile, generate and install VHDL IMEM boot image (for application, no header)
  sim        - in-console simulation using default/simple testbench and GHDL
@@ -288,7 +290,7 @@ The makefile's `CC_OPTS` is exported as **define** to be available within a C pr
 | `-g`                  | Include debugging information/symbols in ELF.
 | `-mstrict-align`      | Unaligned memory accesses cannot be resolved by the hardware and require emulation.
 | `-mbranch-cost=10`    | Branching costs a lot of cycles.
-| `-ffp-contract=off`   | Do not allow contraction of floatind-point operations (no fused operations as they are not supported).
+| `-ffp-contract=off`   | Do not allow contraction of floating-point operations (no fused operations as they are not supported).
 |=======================
 
 :sectnums:
@@ -321,15 +323,23 @@ override USER_FLAGS += "-g -Wl,--__neorv32_heap_size,__heap_size=4096"
 === Executable Image Format
 
 In order to generate an executable for the processors all source files have to be compiled, linked
-and packed into a final executable.
+and packed into a final executable. This executable can be further converted into several image formats.
+
+.Memory Image Formats
+[TIP]
+The NEORV32 software framework includes an <<_executable_image_generator>> than can convert an application
+into several different file formats. These include raw hex files, a proprietary format for uploading via the
+default <<_bootloader>> as well as several standard FPGA memory initialization file types (e.g. `*.coe`,
+`*.mem` and `*.mif`). These image file formats are generated by the according <<_makefile_targets>>.
+
 
 :sectnums:
 ==== Linker Script
 
 After all the application sources have been compiled, they need to be _linked_.
-For this purpose the makefile uses the NEORV32-specific linker scThe linker script defines several sections
+For this purpose the makefile uses the NEORV32-specific linker script. This linker script defines several sections
 for the final executable (compare with <<_address_space>>). However, only the `ram` and `rom` sections are
-relevant for the executable itself; the raining sections are just listed fro completeness.
+relevant for the executable itself; the remaining sections are just listed for completeness.
 
 .Linker script - memory sections
 [cols="<2,<8"]
@@ -486,21 +496,21 @@ The image generator can generate several types of executable file formats select
 [cols="<2,<8"]
 [grid="none"]
 |=======================
-| `-app_bin` | Generates an executable binary file `neorv32_exe.bin` (including header) for UART uploading via the bootloader.
-| `-app_img` | Generates an executable VHDL memory initialization image (no header) for the processor-internal IMEM. This option generates the `rtl/core/neorv32_application_image.vhd` file.
-| `-bld_img` | Generates an executable VHDL memory initialization image (no header) for the processor-internal BOOT ROM. This option generates the `rtl/core/neorv32_bootloader_image.vhd` file.
-| `-raw_hex` | Generates a plain 8x ASCII hex-char file `neorv32_raw_exe.hex` (no header) for custom purpose.
-| `-raw_bin` | Generates a plain binary file `neorv32_raw_exe.bin` (no header) for custom purpose.
-| `-raw_coe` | Generates a COE file `neorv32_raw_exe.coe` (no header) for FPGA memory initialization.
-| `-raw_mem` | Generates a MEM file `neorv32_raw_exe.mem` (no header) for FPGA memory initialization.
+| `-app_bin` | Generates an executable binary file `neorv32_exe.bin` (including bootloader header) for uploading via the bootloader.
+| `-app_img` | Generates an executable VHDL memory initialization image for the processor-internal IMEM. This option regenerates the `rtl/core/neorv32_application_image.vhd` file.
+| `-bld_img` | Generates an executable VHDL memory initialization image for the processor-internal BOOT ROM. This option regenerates the `rtl/core/neorv32_bootloader_image.vhd` file.
+| `-raw_hex` | Generates a raw 8x ASCII hex-char file `neorv32_raw_exe.hex` for custom purpose.
+| `-raw_bin` | Generates a raw binary file `neorv32_raw_exe.bin` for custom purpose.
+| `-raw_coe` | Generates a raw COE file `neorv32_raw_exe.coe` for FPGA memory initialization.
+| `-raw_mem` | Generates a raw MEM file `neorv32_raw_exe.mem` for FPGA memory initialization.
+| `-raw_mif` | Generates a raw MIF file `neorv32_raw_exe.mif` for FPGA memory initialization.
 |=======================
 
-All these options are managed by the makefile. The normal application compilation flow will generate the `neorv32_exe.bin`
-executable designated for uploading via the default NEORV32 bootloader.
+**All these options are managed by the makefile (see <<_makefile_targets>>).**
 
 .Image Generator Compilation
 [NOTE]
-The sources of the image generator are automatically compiled when invoking the makefile (requiring a native GCC installation).
+The sources of the image generator are automatically compiled when invoking the makefile (requiring a _native_ GCC installation).
 
 .Executable Header
 [NOTE]