[website] Self-host latest [stable] API docs

[jackkoenig]

Contributor Checklist

• Did you add Scaladoc to every public function/method?
• Did you add at least one test demonstrating the PR?
• Did you delete any extraneous printlns/debugging code?
• Did you specify the type of improvement?
• Did you add appropriate documentation in docs/src?
• Did you request a desired merge strategy?
• Did you add text to be included in the Release Notes for this change?

Type of Improvement

• Documentation or website-related

Desired Merge Strategy

• Squash

Release Notes

This should enable them to be indexed and thus searchable as part of the website (both by Algolia and by Google).

Reviewer Checklist (only modified by reviewer)

• Did you add the appropriate labels? (Select the most appropriate one based on the "Type of Improvement")
• Did you mark the proper milestone (Bug fix: 3.5.x, 3.6.x, or 5.x depending on impact, API modification or big change: 6.0)?
• Did you review?
• Did you check whether all relevant Contributor checkboxes have been checked?
• Did you do one of the following when ready to merge:
  • Squash: You/ the contributor Enable auto-merge (squash), clean up the commit message, and label with Please Merge.
  • Merge: Ensure that contributor has cleaned up their commit history, then merge with Create a merge commit.

[seldridge]

Can this avoid eval with more normal shell?

Suggested change

	$(eval VER := $(shell cat $(latest_version)))
	$(eval URL := https://repo1.maven.org/maven2/org/chipsalliance/chisel_2.13/$(VER)/chisel_2.13-$(VER)-javadoc.jar)
	cd $(latest_scaladoc_dir) && wget -q -O - $(URL) | tar -x
	VER=$(cat $latest_version)
	URL=https://repo1.maven.org/maven2/org/chipsalliance/chisel_2.13/${VER}/chisel_2.13-${VER}-javadoc.jar
	cd $(latest_scaladoc_dir) && wget -q -O - $URL | tar -x

[jackkoenig]

Unfortunately no, you can't set variables in Makefile rules, so I followed the suggestion here: https://stackoverflow.com/a/1909390

I could maybe just do this as a shell script though. What do you think?