fix: readme link

Author: Adam Janis

website/docs/r/group.html.markdown

@@ -60,7 +60,7 @@ The resource exports the following attributes:
 ## Importing groups
 
 You can import a group state using `terraform import <resource> <id>`.  The
-`id` can be whatever the [details of a group](details_of_a_group) api takes for
+`id` can be whatever the [details of a group][details_of_a_group] api takes for
 its `:id` value, so for example:
 
     terraform import gitlab_group.example example

website/docs/r/project.html.markdown

@@ -67,7 +67,7 @@ The following additional attributes are exported:
 ## Importing projects
 
 You can import a project state using `terraform import <resource> <id>`.  The
-`id` can be whatever the [get single project api](get_single_project) takes for
+`id` can be whatever the [get single project api][get_single_project] takes for
 its `:id` value, so for example:
 
     terraform import gitlab_project.example richardc/example