Update README.md

using-code-ornl-gov/README.md

@@ -18,3 +18,12 @@ for Windows, Mac, and Linux is available here:
 
 https://code.ornl.gov/profile/keys
 
+## Adding members to a project
+
+In order to grant access to other collaborators, you will need to explicitly add
+them to your projects. One important caveat is that before you can add them, 
+they must first log in to [code.ornl.gov](https://code.ornl.gov) so that gitlab
+will recognize their UCAMS/XCAMS account. Once they have successfully logged in,
+you can add them by following the instructions here:
+
+[code.ornl.gov](https://code.ornl.gov)
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