Tweaks to talks.html (new website)

[LukeMoll]

123 had too many differences with HEAD so it was cleaner to replicate the changes here.

Fixes #96.

[LukeMoll]

NB: 48d34aa changes the format_date function in filters.py so that dates now display as 2nd January, 2022. This is also used for talks (sans the year)

[sersorrel]

smallest of nits:

• "At the request of the speaker, this talk will not be recorded." s/will not be/was not/, imo
• the <details> don't have the same cursor:pointer or underline effects as the ones on the minutes page, idk if that's a thing that will sort itself once this is merged? not enough brain to work out where that new styling for the minutes page lives
• the <hr> between "Giving a talk" and the list of past talks doesn't look awesome imo (might look better if there was text under the noticebox? vague memory of someone pointing out that there was text there at some point)

[LukeMoll]

There was text, it's a content issue but it'd be nice to have that back It's intended to separate this term's talks from the previous terms' talks (without problematic asymmetric headings), possibly giving it non-default styling would help that

[LukeMoll]

Documentation of talk() macro required @LukeMoll

[LukeMoll]

Have updated spacing a bit, now features same hover-over actions as in new minutes.html

[LukeMoll]

@LukeMoll talks.html is now no longer a "simple page"

Fixed in db96425

[LukeMoll]

@LukeMoll Also current CSS in minutes.html (on main) looks bad in mobile view; while you're messing around with <details> CSS make sure that's fixed

Main:

This branch: