fix spell findings in installation guides and Contributing.md

Signed-off-by: Dietrich Krönke <dietrich.kroenke@apex.ai>

CONTRIBUTING.md

@@ -128,7 +128,7 @@ We use [Google test](https://github.com/google/googletest) for our unit and inte
 with the version 1.8.1.
 
 Have a look at our [best practice guidelines](./doc/website/advanced/best-practice-for-testing.md) for writing tests and
-[Installation guide for contributors](./doc/website/advanced/installation-guide-for-contributors.md#build-and-run-tests) for building them.
+[installation guide for contributors](./doc/website/advanced/installation-guide-for-contributors.md#build-and-run-tests) for building them.
 
 ### Unit tests (aka module tests)
 

doc/website/advanced/installation-guide-for-contributors.md

@@ -37,7 +37,8 @@ The source code of the tests is placed into the folder `test` within the differe
 If you now want to create a new test you can place the sourcefile directly into the right folder. CMake will automatically detect the new file when doing a clean build and will add it to a executable. There is no need to add a gtest main function because we already provide it.
 For every test level are executables created, for example `posh_moduletests`. They are placed into the corresponding build folder (e.g. `iceoryx/build/posh/test/posh_moduletests`).
 
-If you want to execute only individual testcases then you can use these executables together with a gtest filter. Let's assume you want to execute only the `ServiceDescription_test` from the posh_moduletests, then you can do the following:
+If you want to execute only individual test cases, you can use these executables together with a filter command.
+Let's assume you want to execute only `ServiceDescription_test` from posh_moduletests:
 
 ```bash
 ./build/posh/test/posh_moduletests --gtest_filter="ServiceDescription_test*"

doc/website/getting-started/installation.md

@@ -114,7 +114,7 @@ The `CMakeLists.txt` from `iceoryx_meta` can be used to easily develop iceoryx w
     ```
 
     !!! tip
-        You can fasten up the build by appending `-j 4` where 4 stands for the number of parallel build processes.
+        You can speed up the build by appending `-j 4` where 4 stands for the number of parallel build processes.
         You can choose more or less depending on your available CPU cores on your machine.
 
 4. Install to system
@@ -165,7 +165,7 @@ The script currently works for Linux and QNX only, it is planned to offer a mult
     !!! note
         The build script is installing the header files and binaries into `build/install/prefix`.
 
-You can use the `help` argument for getting an overview over the available options:
+You can use the `help` argument for getting an overview of the available options:
 
 ```bash
 ./tools/iceoryx_build_test.sh help