add 'loop' to highlighted keywords (#103)

* add 'loop' to highlighted keywords

Just add highlight for the keyword `loop` which can be used instead of `with_<lookup> since ansible 2.5 : https://docs.ansible.com/ansible/latest/user_guide/playbooks_loops.html

Co-authored-by: masao77

Author: masao77

README.md

@@ -113,7 +113,7 @@ Accepts any syntax group-name from `:help E669` - e.g. _Comment_, _Constant_, an
 
 *Note:* Defaults to 'Statement' when not set.
 
-This option changes the highlight of all `with_.+` keywords in playbooks.
+This option changes the highlight of all `with_.+` keywords and `loop` in playbooks.
 
 ##### g:ansible_template_syntaxes
 `let g:ansible_template_syntaxes = { '*.rb.j2': 'ruby' }`

syntax/ansible.vim

@@ -101,4 +101,11 @@ else
   highlight default link ansible_with_keywords Statement
 endif
 
+execute 'syn keyword ansible_with_keywords loop containedin='.s:yamlKey.' contained'
+if exists("g:ansible_with_keywords_highlight")
+  execute 'highlight link ansible_with_keywords '.g:ansible_with_keywords_highlight
+else
+  highlight default link ansible_with_keywords Statement
+endif
+
 let b:current_syntax = "ansible"