Add docs for deleting backups

[a-mccarthy]

Signed-off-by: Abigail McCarthy [email protected]

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Please add a summary of your change

This PR updates the backup reference page to include more information around deleting backups

Does your change fix a particular issue?

Fixes #1712

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• Accepted the DCO. Commits without the DCO will delay acceptance.
• Created a changelog file or added /kind changelog-not-required as a comment on this pull request.
• Updated the corresponding documentation in site/content/docs/main.

[a-mccarthy]

For this PR i'd like to make sure that each example is correct. And hopefully provide a better example for using DeleteBackupRequest. I have an issue to cover documenting DeleteBackupRequest, #4813, which are not mentioned in the docs at the moment.

[codecov-commenter]

Codecov Report

Merging #4850 (dca7497) into main (65db258) will decrease coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #4850      +/-   ##
==========================================
- Coverage   41.41%   41.37%   -0.05%     
==========================================
  Files         204      204              
  Lines       17948    18061     +113     
==========================================
+ Hits         7434     7473      +39     
- Misses       9970    10041      +71     
- Partials      544      547       +3     

Impacted Files	Coverage Δ
pkg/controller/backup_sync_controller.go	61.53% <0.00%> (-3.33%)	⬇️
pkg/persistence/object_store.go	57.77% <0.00%> (-2.73%)	⬇️
pkg/controller/backup_controller.go	57.37% <0.00%> (-1.78%)	⬇️
pkg/restic/exec_commands.go	15.38% <0.00%> (-0.81%)	⬇️
pkg/controller/pod_volume_restore_controller.go	23.34% <0.00%> (-0.53%)	⬇️
pkg/cmd/server/server.go	6.75% <0.00%> (-0.04%)	⬇️
pkg/restic/command_factory.go	93.50% <0.00%> (+0.08%)	⬆️
pkg/controller/pod_volume_backup_controller.go	44.91% <0.00%> (+0.16%)	⬆️
pkg/persistence/object_store_layout.go	91.83% <0.00%> (+0.34%)	⬆️
pkg/restore/restore.go	66.69% <0.00%> (+0.69%)	⬆️
... and 2 more

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[ywk253100]

There isn't any doc for DeleteBackupRequest CR spec on Velero's official doc site, users don't know how to send the request without checking the code.

Suggest adding the DeleteBackupRequest spec in our doc or just remove the line 92 as this is kind of internal implementation detial

[a-mccarthy]

@ywk253100 thanks for the background information about DeleteBackupRequest. I've removed it from this PR, please review again if you have a chance