yml config documentation (#2899)

* little fix

* add config hints

* doc link

.appveyor.yml

@@ -94,3 +94,6 @@ deploy:
   force_update: true
   on:
     appveyor_repo_tag: true
+
+# official validator for ".appveyor.yml" config file: https://ci.appveyor.com/tools/validate-yaml
+# appveyor config documentation: https://www.appveyor.com/docs/build-configuration/

.codacy.yml

@@ -2,4 +2,4 @@
 exclude_paths:
   - '**/translations/*.ts'
 
-# see https://support.codacy.com/hc/en-us/articles/115002130625-Codacy-Configuration-File
+# codacy config documentation: https://support.codacy.com/hc/en-us/articles/115002130625-Codacy-Configuration-File

.travis.yml

@@ -56,5 +56,5 @@ notifications:
     on_failure: change
     on_start: never
     
-# official validator for travis.yml config files: https://yaml.travis-ci.org
-# travis documentation: https://docs.travis-ci.com/user/customizing-the-build
+# official validator for ".travis.yml" config file: https://yaml.travis-ci.org
+# travis config documentation: https://docs.travis-ci.com/user/customizing-the-build