improve docs

gradle/Earthfile

@@ -12,8 +12,7 @@ VERSION --global-cache 0.7
 GRADLE_GET_MOUNT_CACHE:
     COMMAND
     ARG EARTHLY_TARGET_PROJECT_NO_TAG
-    ARG OS_RELEASE=$(md5sum /etc/os-release | cut -d ' ' -f 1)
-    ARG cache_prefix = "${EARTHLY_TARGET_PROJECT_NO_TAG}#${OS_RELEASE}#earthly-gradle-cache"
+    ARG cache_prefix = "${EARTHLY_TARGET_PROJECT_NO_TAG}#earthly-gradle-cache"
     IF [ "$GRADLE_USER_HOME" = "" ]
         ENV GRADLE_USER_HOME="$HOME/.gradle"
     END

gradle/README.md

@@ -11,18 +11,23 @@ IMPORT github.com/earthly/lib/gradle:<version/commit> AS gradle
 
 ## +GRADLE_GET_MOUNT_CACHE
 
-This function sets the following entries in the calling environment, so they can be used later on `RUN` commands
-- `$EARTHLY_GRADLE_USER_HOME_CACHE`: Code of the mount cache for the gradle home.
-- `$EARTHLY_GRADLE_PROJECT_CACHE`: Code of the mount cache for the .gradle folder.
+This function sets the following entries in the calling environment, so they can be used later to parametrize two global mount caches in `RUN` commands:
+- `$EARTHLY_GRADLE_USER_HOME_CACHE`: Code of the mount cache for the [gradle user home](https://docs.gradle.org/current/userguide/directory_layout.html#dir:gradle_user_home) directory.
+- `$EARTHLY_GRADLE_PROJECT_CACHE`: Code of the mount cache for the [gradle project root](https://docs.gradle.org/current/userguide/directory_layout.html#dir:project_root) directory.
 
-### Arguments:
+### Arguments
 - `cache_prefix`: To be used in both caches. By default: `${EARTHLY_TARGET_PROJECT_NO_TAG}#${OS_RELEASE}#earthly-gradle-cache`
 
-### Example:
+### Example
 ```earthly
 DO gradle+GRADLE_GET_MOUNT_CACHE
 RUN --mount=$EARTHLY_GRADLE_USER_HOME_CACHE --mount=$EARTHLY_GRADLE_PROJECT_CACHE gradle --no-daemon build
 ```
 
+### Scoping
+
+If `cache_prefix` is not set, the two global caches have an Earthfile-scope, that is, they are not shared with other Earthfiles.
+Otherwise, all Earthfiles using the same `cache_prefix` will share the cache mounts.
+
 ## Example
 See [earthly-intellij-plugin](https://github.com/earthly/earthly-intellij-plugin/blob/main/Earthfile) for a complete example.