docs_pull_request: Add parameters highlighting

Added highlighting to parameter references in docs so that they standout a bit better.
Filter name is singular
Uniform spacing across all filter examples
Fix path to index.html when launching browser
Add link to ansible-examples repo
Add link (with minor rewording) to jinja2 builtin filters
Merge branch 'postgres_alter_role' of https://github.com/jinnko/ansible into jinnko-postgres_alter_role

Conflicts:
	library/database/postgresql_user
Merge branch 'fix-postgres_user_to_understand_pg_namespaces' of https://github.com/alanfairless/ansible into alanfairless-fix-postgres_user_to_understand_pg_namespaces
Merge pull request #6038 from mmoya/docfix

Doc improvements / fixes
Merge remote-tracking branch 'berendt/fixing_permissions' into pull_4703
Merge pull request #6043 from risaacson/pull_4703

I had to remerge this as the original would not automerge. #4703
Sanitize sudo success_key from stdout for raw/script modules

Fixes #5533
Closes #5605
Closes #5606
Closes #5607
Make sure unicode params don't break logging in modules
Merge branch 'patch-1' of https://github.com/eggsby/ansible into eggsby-patch-1
Tweak library installation path to default to /usr/share/ansible if specified
Merge branch 'fix-5679' of https://github.com/jirutka/ansible into jirutka-fix-5679
Merge branch 'devel' of https://github.com/calebbrown/ansible into calebbrown-devel
Avoid breaking on unicode input when logging to syslog in modules

After commit 254f87e, non-ascii input broke logging to syslog.
allow ansible_ssh_private_key_file to be templated (thanks to benno)
removed comment