Readme update (#16)

* readme

* test config fix

* example config

Author: AndWeHaveAPlan

.github/workflows/build-cargo.yml

@@ -51,6 +51,9 @@ jobs:
             endpointUrl = "http://localhost:9000"
             bucketName = "forklift"
             useSSL = false
+          [cache.extraMetadata]
+            github_run_id="$GITHUB_RUN_ID"
+            github_job="$GITHUB_JOB"
           '
 
       - name: Checkout cargo 1

README.MD

@@ -26,7 +26,7 @@ Forklift acts as a `rustc` wrapper and decides whether to use the cache based on
 
 3. The wrapper gathers dependencies (`--extern name=path`) and forwards them to the server to verify if any of these dependencies have been rebuilt during this "session".
 
-4. The wrapper computes the cache key from the `rustc` arguments (which already include the cargo hash), the output path, the hash of the source files, and the hash of the dependencies' artifacts.
+4. The wrapper computes the cache key from the `rustc` arguments (which already include the cargo hash), the output path, the hash of the source files, hash of the rustc binary, and the hash of the 'dependencies' artifacts.
 
 5. **If there are any rebuilt dependencies** or the cache package is not present in the storage, Forklift will execute the specified `rustc` command, collect its output, and upload it to the server.
 
@@ -91,9 +91,10 @@ See `forklift config --help` for more info.
 #### cache
 `[cache]`
 
-| key      | type     | description                                                      |
-|----------|----------|------------------------------------------------------------------|
-| extraEnv | []string | Additional environment variable names for cache key calculations |
+| key           | type              | description                                                      |
+|---------------|-------------------|------------------------------------------------------------------|
+| extraEnv      | []string          | Additional environment variable names for cache key calculations |
+| extraMetadata | map[string]string | Additional fields to include in artifact metadata. If the value starts with a dollar sign ($), Forklift will attempt to resolve the environment variable during upload. |
 
 #### storage
 `[storage]`

config-example.toml

@@ -6,6 +6,10 @@ threadscount = 10
 [cache]
 extraEnv = ["SOME_VAR"]
 
+[cache.extraMetadata]
+  github_run_id="$GITHUB_RUN_ID"
+  github_job="$GITHUB_JOB"
+
 [compression]
 type = "zstd"