Blog pages should contain page-meta-lastmod.html too

[chalin]

@LisaFC et all: are you aware of any reason why blog pages don't contain "last mod" info like regular doc pages do?

Some context:

• _default:

  docsy/layouts/_default/content.html

  Line 19 in 519930c

  {{ partial "page-meta-lastmod.html" . }}

• The blog content.html override omits page-meta-lastmod.html

If there's no reason that you're aware of to omit that info at the bottom of the page, I suggest that we add it. Thoughts?

[chalin]

I've quickly experimented with this and it looks best if we end the <div> in https://github.com/google/docsy/blob/main/layouts/blog/content.html with page-meta-lastmod.html last:

{{ partial "pager.html" . }}
{{ partial "page-meta-lastmod.html" . }}

For example:

[LisaFC]

Happy to add it if you think it's useful - I think the main reason we didn't was that blog posts tend not to be updated (unless someone discovers an error post-publication) and have a publication date already. If they're being regularly updated they probably have content that should be in regular user docs. :)

Can't remember the issue/PR I commented on but I also think we should probably have a different "page meta links" for blog posts as most projects probably don't want to be inviting other users to edit guest blog posts. Thoughts?