User Guide: Update near filter

[keif888]

This documentation update is associated to PR photoprism/photoprism#5195, and notes that near now supports the | symbol to allow multiple UIDs.

[lastzero]

Have you also updated it in the form struct annotations, from which these docs are generated? See the internal/form package.

[keif888]

I have now and it's been pushed to photoprism/photoprism#5195.
I didn't realise that these were generated from there.