Add note about setting $ELECTRON_GITHUB_TOKEN

docs/development/releasing.md

@@ -43,6 +43,7 @@ Merge the temporary back into master, without creating a merge commit:
 
 ```sh
 git merge release master --no-commit
+git push origin master
 ```
 
 If this fails, rebase with master and rebuild:
@@ -65,6 +66,12 @@ npm start
 
 Verify the window is displaying the current updated version.
 
+## Set `$ELECTRON_GITHUB_TOKEN`
+
+Create a personal access token with "repo" scope, and set it in your environment as `ELECTRON_GITHUB_TOKEN`.
+
+You will only need to do this once.
+
 ## Publish the release
 
 This script will download the binaries and generate the node headers and the .lib linker used on Windows by node-gyp to build native modules.