Documentation: add new section to release docs about troubleshooting …

…the release (#56436)

docs/contributors/code/release.md

@@ -25,6 +25,7 @@ Similar requirements apply to releasing WordPress's [npm packages](https://devel
             -   [Automated cherry-picking](#automated-cherry-picking)
             -   [Manual cherry-picking](#manual-cherry-picking)
         -   [Publishing the release](#publishing-the-release)
+        -   [Troubleshooting the release](#troubleshooting-the-release)
     -   [Documenting the release](#documenting-the-release)
         -   [Selecting the release highlights](#selecting-the-release-highlights)
         -   [Requesting release assets](#requesting-release-assets)
@@ -253,6 +254,41 @@ Once approved, the new Gutenberg version will be available to WordPress users al
 
 The final step is to write a release post on [make.wordpress.org/core](https://make.wordpress.org/core/). You can find some tips on that below.
 
+#### Troubleshooting the release
+
+> The plugin was published to the WordPress.org plugin directory but the workflow failed.
+
+This has happened ocassionally, see [this one](https://github.com/WordPress/gutenberg/actions/runs/6955409957/job/18924124118) for example.
+
+It's important to check that:
+
+- the plugin from the directory works as expected
+- the ZIP contents (see [Downloads](https://plugins.trac.wordpress.org/browser/gutenberg/)) looks correct (doesn't have anything obvious missing)
+- the [Gutenberg SVN repo](https://plugins.trac.wordpress.org/browser/gutenberg/) has two new commits (see [the log](https://plugins.trac.wordpress.org/browser/gutenberg/)):
+  - the `trunk` folder should have "Commiting version X.Y.Z"
+  - there is a new `tags/X.Y.Z` folder with the same contents as `trunk` whose latest commit is "Tagging version X.Y.Z"
+
+Most likely, the tag folder couldn't be created. This is a [known issue](https://plugins.trac.wordpress.org/browser/gutenberg/) that [can be fixed manually](https://github.com/WordPress/gutenberg/issues/55295#issuecomment-1759292978).
+
+Either substitute SVN_USERNAME, SVN_PASSWORD, and VERSION for the proper values or set them as global environment variables first:
+
+```sh
+# CHECKOUT THE REPOSITORY
+svn checkout https://plugins.svn.wordpress.org/gutenberg/trunk --username "$SVN_USERNAME" --password "$SVN_PASSWORD" gutenberg-svn
+
+# MOVE TO THE LOCAL FOLDER
+cd gutenberg-svn
+
+# IF YOU HAPPEN TO HAVE ALREADY THE REPO LOCALLY
+# AND DIDN'T CHECKOUT, MAKE SURE IT IS UPDATED
+# svn up .
+
+# COPY CURRENT TRUNK INTO THE NEW TAGS FOLDER
+svn copy https://plugins.svn.wordpress.org/gutenberg/trunk https://plugins.svn.wordpress.org/gutenberg/tags/$VERSION -m 'Tagging version $VERSION' --no-auth-cache --non-interactive  --username "$SVN_USERNAME" --password "$SVN_PASSWORD"
+```
+
+Ask around if you need help with any of this.
+
 ### Documenting the release
 
 Documenting the release is led by the release manager with the help of [Gutenberg development team](https://developer.wordpress.org/block-editor/block-editor/contributors/repository-management/#teams) members. This process is comprised of a series of sequential steps that, because of the number of people involved, and the coordination required, need to adhere to a timeline between the RC and stable releases. Stable Gutenberg releases happen on Wednesdays, one week after the initial RC.