use credential settings for release repo access

Use the credential settings in '~/.gitconfig' instead of the custom bloom configuration file in order to avoid maintaining an additional file with tokens and to avoid mapping https to ssh.

Signed-off-by: Christian Rauch <[email protected]>

Author: christian-rauch

source/How-To-Guides/Releasing/_Personal-Access-Token.rst

@@ -27,3 +27,18 @@ Save your GitHub username and PAT to a new file called ``~/.config/bloom``, with
       "github_user": "<your-github-username>",
       "oauth_token": "<token-you-created-for-bloom>"
    }
+
+Configure in your ``~/.gitconfig`` that your GitHub account and PAT are used for all release repositories under https://github.com/ros2-gbp:
+
+.. code-block:: ini
+
+    [credential "https://github.com/ros2-gbp"]
+        username = x-access-token
+        helper = "!f() { test \"$1\" = get && echo \"password=<token-you-created-for-bloom>\"; }; f"
+
+You can additionally use different GitHub accounts and PATs for different release repos:
+
+.. code-block:: ini
+    [credential "https://github.com/ros2-gbp/my_package-release.git"]
+        username = x-access-token
+        helper = "!f() { test \"$1\" = get && echo \"password=<other-token-you-created-for-bloom>\"; }; f"