Feature request: created / modified timestamp metadata per block

[simonratner]

Have you searched existing Github issues to see if someone has already requested this feature?
Yes

Is your feature request related to a problem? Please describe.
Being able to easily see when a note was made or last modified.

Describe the solution you'd like
Small-print timestamp in top right corner of each block
or, tooltip when hovering over block margin with block metadata such as timestamps.

Describe alternatives you've considered
Per-line modified history, so e.g. each line in a list could have an added/modified timestamp when you hover over the line number in the margin - would be interesting for todo/task lists, and automatically subsumes the need for block-level metadata.