README.md in slugbuilder-3.0.0 vs README.md in slugbuilder-3.1.0

@@ -96,11 +96,11 @@
 
 ### Builder#build(slug_name: nil, clear_cache: false, env: {}, buildpacks: Slugbuilder.config.buildpacks, prebuild: nil, postbuild: nil, &block)
 
 `build` builds the slug and writes build information to `STDOUT`.
 
-- `slug_name` String (optional): Override default name of slug (repo.git_ref.git_sha.tgz with the `/` in repo replaced by `.`)
+- `slug_name` String (optional): Override default name of slug (repo.git_ref.git_sha.random_hex.tgz with the `/` in repo replaced by `.`)
 - `clear_cache` Boolean (optional): destroys the cache before building when true
 - `env` Hash (optional): an optional hash of environment variables
 - `buildpacks` Array (optional): optionally set buildpacks to be used for that particular build. defaults to `Slugbuilder.config.buildpacks`. Buildpacks should be in the form `<organization>/<repository_name>`, `https://<git_service>/<organization>/<repository_name>.git`, or `git@<git_service>:<organization>/<repository_name>.git`
 - `prebuild` Proc (optional): an optional Proc (or anything that conforms to the `call` API of a Proc) that will be run before the build. The Proc will receive a Hash with the structure:
   - `repo` String: The git repo identifier
@@ -160,10 +160,10 @@
 
 > Defaults to `/tmp/slugbuilder`
 
 **cache_dir**
 
-This is the directory where the cache lives.
+This is the directory where the cache lives. Each repo has its own cache (eg. `cache-dir/org/repo`)
 
 > Defaults to `/tmp/slugbuilder-cache`
 
 **output_dir**