chore(cardano-chain-follower): Add some READMEs to the cardano-chain-…

…follower overhead benchmark

.config/dictionaries/project.dic

@@ -45,6 +45,7 @@ Datelike
 dreps
 encryptor
 Errno
+Earthfile
 excalidraw
 fadvise
 fcntl

hermes/crates/cardano-chain-follower/testbed/README.md

@@ -0,0 +1,5 @@
+# Testbed
+
+This workspace contains test scenarios for the `cardano-chain-follower` crate
+in order the measure implementation details that are not so easily tested by
+automated test frameworks.

hermes/crates/cardano-chain-follower/testbed/overhead_benchmark/README.md

@@ -0,0 +1,27 @@
+# Overhead Benchmark
+
+The purpose of this benchmark is to measure the overhead that using the `cardano-chain-follower` crate
+has on top of the `pallas` crate which is used to implement most of the chain follower features.
+
+## Running
+
+In order to execute the benchmark you need a valid Mithril snapshot to point it to.
+It doesn't matter which network the snapshot is from because the benchmark will only read the data from it.
+
+There are 2 modes in which the benchmark can be executed:
+
+| Benchmark name           | Description  |
+---------------------------|--------------|
+| pallas                 | When executed with `--bench-name pallas`, the benchmark reads the Mithril snapshot from origin to its tip using only the `pallas` crate mechanisms |
+| cardano‑chain‑follower | When executed with `--bench-name cardano-chain-follower` it uses the `cardano-chain-follower` crate to follow the chain from origin to the tip of the specified snapshot |
+
+One way of executing the benchmark is as follows:
+
+```sh
+cargo run --release -- --bench-name cardano-chain-follower --mithril-snapshot-path PATH_TO_MITHRIL_SNAPSHOT
+```
+
+## Earthfile
+
+The Earthfile has targets for building and running the benchmark.
+It also contains targets to fetch Mithril snapshots and save them locally.