docs(custom_property): fix typo and import example (#2605)

s/comibnation/combination

remove tags from import example that don't render properly on the TF registry

Author: scarlson

website/docs/r/repository_custom_property.html.markdown

@@ -40,7 +40,7 @@ The following arguments are supported:
 
 ## Import
 
-GitHub Repository Custom Property can be imported using an ID made up of a comibnation of the names of the organization, repository, custom property separated by a `:` character, e.g.
+GitHub Repository Custom Property can be imported using an ID made up of a combination of the names of the organization, repository, custom property separated by a `:` character, e.g.
 
 ```
 $ terraform import github_repository_custom_property.example organization-name:repo-name:custom-property-name