feat(adminmanual): Add section about CardDAV rate limits

[joshtrichards]

☑️ Resolves

• Fix fix(dav): Rate limit address book creation server#44664 (docs weren't created prior to merging the feature)

Just a simple adaption of #11565 to accommodate similar functionality recently added for CardDAV.

Note, the feature as implemented has a small typo in the config parameter (maximumAdressbooks). Since it's already in the wild, I documented it to match the implementation as-is.

🖼️ Screenshots

[joshtrichards]

/backport to stable30

[joshtrichards]

/backport to stable29

[joshtrichards]

/backport to stable28

[backportbot]

The backport to stable28 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable28
git pull origin stable28

# Create the new backport branch
git checkout -b backport/12161/stable28

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 50f54e15

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/12161/stable28

Error: No changes found in backport branch

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Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.