Update documentation to explain when cleaning the cache might be necessary

Would it be possible to either update `release_diff` to run with the `-B` option as standard, or update the usage notes in the commands reference at the bottom of the Makefile to explicitly state to use the option?

For context, the Makefile currently suggests under "Tricks":
`* Add -B to the end of your command to force re-running it even if nothing has changed`

As a "lay" user, I assumed this didn't apply to `release_diff`, since things clearly had changed and the current release would be dynamically pulled in every time I ran the command. I was therefore surprised to find that every time I ran the command before a release, the diff was against an older version of the ontology, so I always had to run a manual `robot diff` instead until @matentzn pointed me in the right direction.

Please either refactor the Makefile for `release_diff` to pull in `current_release.owl` each time it is run rather than using the cached version, or update the usage notes to make it clear that the `-B` option is required and appropriate in this scenario.

Start in the Makefile's `release_diff` target and the commands reference under "Tricks." Check how `release_diff` uses the cached `current_release.owl`, then compare that behavior with the documented `-B` option and the manual `robot diff` workaround. Done means either the target refreshes the release input on each run or the usage notes clearly explain when `-B` is required.

Written by the indexing model from the issue text.