📖 Add additional post-release step to release docs

[furkatgofurov7]

What this PR does / why we need it:
Going forward, when a new Turtles minor/major release will be published, we need to make sure Turtles Product Docs is synced and contains up-to-date versions of docs available for users. This patch adds notes about additional post-release step to releasing documentation about syncing the Community Docs of Turtles with the Product Docs available in https://documentation.suse.com/cloudnative/cluster-api/v0.11/en/index.html

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:
Reference JIRA ticket to sync v0.12 Community Docs version with Product Docs.

Checklist:

• squashed commits into logical changes
• includes documentation
• adds unit tests
• adds or updates e2e tests