.pre-commit-config.yaml: Do not set ANSIBLE_LIBRARY for ansible-doc-test

With latest Ansible (4.0.0) it is needed to have a complete path for
ANSIBLE_LIBRARY. It is not good to hard code this in the
.pre-commit-config.yaml file for plugins and also all roles. Instead
it will be set in ansible-doc-test as it knows the path for each file
that is checked.

.pre-commit-config.yaml

@@ -26,6 +26,6 @@ repos:
   - id: ansible-doc-test
     name: Verify Ansible roles and module documentation.
     language: python
-    entry: env ANSIBLE_LIBRARY=./plugins/modules utils/ansible-doc-test
+    entry: utils/ansible-doc-test
     # args: ['-v', 'roles', 'plugins']
     files: ^.*.py$