Followup on EEG Browser 28 changes

[christinerogers]

Followup PR to #10062 to include these considerations:

• configurable HED Endorsement (useHEDendorsement Yes/No) since some LORISes may not use endorsement
• maybe also configurable HED support/visibility ; since some LORISes may not want users to add tags (useHEDtags config; and/or permission to add, which would also need to be project-specific)
• documentation on these features (e.g. module markdown, changelog)
• note if above configs are added, help text displayed should also be governed by this config

Originally posted by @christinerogers in #10062 (comment)

Also to do: review behaviours reported here and evaluate relevance/ imkportance

• e.g. can't undo own caveat