UPGRADE: sphinx-togglebutton v0.3.0

[choldgraf]

This PR does 2 things:

• Raises the pin on sphinx-togglebutton to ~= 0.3.0, so that we get the new UI elements that it introduced
• Removes some of the specific instructions in our "hide markdown content" section, because (I believe) we deprecated the ability to hide markdown cells with a cell tag, and so that content was out-of-date. This section now links out to the sphinx-togglebutton and sphinx-design docs, since myst-nb isn't directly responsible for hiding regular ol' content blocks.

I know we have a big rewrite in the works but I don't think this will affect that since this is just a version bump + docs

[codecov]

Codecov Report

Merging #390 (5d6bc62) into master (5f4b8f6) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #390   +/-   ##
=======================================
  Coverage   87.35%   87.35%           
=======================================
  Files          12       12           
  Lines        1368     1368           
=======================================
  Hits         1195     1195           
  Misses        173      173           

Flag	Coverage Δ
pytests	87.35% <ø> (ø)

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[choldgraf]

Hmmm - the regression failures seem related to the myst-nb execution phase. If this is a non-trivial fix then maybe I'll just wait until #380 is in before bumping sphinx-togglebutton, or maybe @chrisjsewell can bump the version as a part of #380 ?

EDIT: The test errors were due to a recent release of pandas (1.4) raising warnings that broke our regression tests, so I've pinned it in our test suite similar to what we're doing with matplotlib.

[choldgraf]

I'll plan on merging this in a day or so, and cutting a 0.13.2 release, so that we can see these changes in the book theme and update more CSS if need be, unless I hear any objections before then (in particular I don't wanna mess up @chrisjsewell in #380 so lemme know if this would be disruptive)

[choldgraf]

OK, I haven't got any objections so I'm merging this one in. Will cut a 0.13.2 release while I'm at it

[chrisjsewell]

Yeh I think it's fine cheers