Fix pre-commit hook config (#164)

Moved gitlint args from pre-commit's entry to args.

Updated docs to reflect best way to add additional arguments.

Closes #163

.pre-commit-hooks.yaml

@@ -1,5 +1,6 @@
 -   id: gitlint
     name: gitlint
     language: python
-    entry: gitlint --staged --msg-filename
+    entry: gitlint
+    args: [--staged, --msg-filename]
     stages: [commit-msg]

docs/index.md

@@ -219,11 +219,14 @@ your `.pre-commit-config.yaml` file like so:
     rev:  # Fill in a tag / sha here
     hooks:
     -   id: gitlint
-        stages: [commit-msg]
-        entry: gitlint
         args: [--contrib=CT1, --msg-filename]
 ```
 
+!!! important
+
+   You need to add `--msg-filename` at the end of your custom `args` list as the gitlint-hook will fail otherwise.
+
+
 ## Using gitlint in a CI environment
 By default, when just running `gitlint` without additional parameters, gitlint lints the last commit in the current
 working directory.
@@ -426,4 +429,4 @@ Exit Code  | Description
 -----------|------------------------------------------------------------
 253        | Wrong invocation of the `gitlint` command.
 254        | Something went wrong when invoking git.
-255        | Invalid gitlint configuration
+255        | Invalid gitlint configuration