Docs repo is too big to deploy

[WardBrian]

The GitHub Pages limits page states that you will not be able to serve a github pages repository that is larger than 1GB, which as of this morning our deployment here now is. This is blocking the docs being published for the new 2.38 release (stan-dev/cmdstan#1333)

Most of the size is from the old, pre-quarto docs. Here's the breakdown:

1.2G    .
82M     2_33
81M     2_32
80M     2_31
79M     2_30
74M     2_29
68M     2_28
65M     2_27
63M     2_26
63M     2_25
62M     2_24
57M     2_23
46M     2_22
46M     2_21
46M     2_20
45M     2_19
44M     2_18
24M     2_38
24M     2_37
23M     2_36
23M     2_35
22M     2_34
6.7M    stan-users-guide
4.1M    functions-reference
3.7M    search.json
2.5M    reference-manual
1.7M    site_libs
1.5M    cmdstan-guide
644K    sdlc.html
392K    img
52K     index.html
32K     404.html
12K     theming
12K     quarto-config
8.0K    quarto_styles.css
4.0K    google9e4c7002947f3d44.html

[WardBrian]

It looks like one build eventually succeeded, but I suspect we will need to do something before the next release.

[jgabry]

Is one option to move docs from very old releases to a separate repo?

[WardBrian]

That would be reasonable.

We'd want to generate redirects to them to keep very-old links resolving in things like the case studies, but we have that ability in this repo, and the result would likely be much smaller -- the pre-Quarto docs are most of the size, so that seems like a reasonable cutoff to look into

[bob-carpenter]

A side benefit would be making all the old versions have dead links so Google finally clears them out. Google search typically yields versions of docs that are many years out of date and the links are only so-so over time.