Mention upstream branch creation on component guide

Add additional steps when updating components from a new Debian release
in order to also create `upstream` branch.

Signed-off-by: Walter Lozano <walter.lozano@collabora.com>

content/guides/component_guide.md

@@ -231,15 +231,17 @@ each `apertis/*` branch that requires updating.
 ## Updating Components to a New Debian Release
 
 The CI/CD pipeline can also be used to pull in a new release of Debian. 
-If the needed `debian/$RELEASE` branch doesn't exist (for example, there is a
-`debian/buster` branch but no `debian/bullseye`), the Gitlab Web UI can be used
-to create it:
+If the needed `debian/$RELEASE` and `upstream/$RELESASE` branches don't exist
+(for example, there are `debian/buster` and `upstream/buster` branches but no
+`debian/bullseye` and `upstream/bullseye`), the Gitlab Web UI can be used
+to create them:
 - Navigate to the `Branches` page and click on the `New branch` button.
 - Enter the new branch name as `debian/$RELEASE`, where `$RELEASE` is the new
   release name, for example `debian/bullseye`.
 - In the `Create from` field select the previous Debian release. For example,
   the release that precedes Debian Bullseye is Buster, so pick `debian/buster`.
 - Click the `Create branch` button.
+- Repeat the steps for `upstream/$RELEASE`.
 
 In some situations manual intervention may be required to tweak the packaging,
 patches or the automated merge machinery may ask to `PLEASE SUMMARIZE remaining