displayed page modification date incorrect

[Gerwin Klein]

The footer shows site modification and page modification dates, but it looks like they are always the same and might always just be when the site got last generated.

[Kent McLeod]

The timestamp is extracted from the git history: https://github.com/seL4/docs/blob/master/Makefile#L33

Looks like the github action for checking out is only doing depth 1 which results in all pages being last modified in the same commit:

    # Number of commits to fetch. 0 indicates all history for all branches and tags.
    # Default: 1
    fetch-depth: ''

[Gerwin Klein]

Thanks for tracking that down, I'll change it to full depth.