Add runners_token documentation

Author: mcanevet

website/docs/d/project.html.markdown

@@ -57,5 +57,4 @@ The following attributes are exported:
 
 * `web_url` - URL that can be used to find the project in a browser.
 
-
-
+* `runners_token` - Registration token to use during runner setup.

website/docs/r/project.html.markdown

@@ -64,6 +64,8 @@ The following additional attributes are exported:
 
 * `web_url` - URL that can be used to find the project in a browser.
 
+* `runners_token` - Registration token to use during runner setup.
+
 ## Importing projects
 
 You can import a project state using `terraform import <resource> <id>`.  The