8215131: Pandoc 2.3/build documentation fixes

[gdams]

changes apply cleanly except for the cross-compile markdown table which was updated in 90ac8ae

Prerequisite to backporting openjdk/jdk@4f45b5f

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Integration blocker

 ⚠️ Dependency #1313 must be integrated first

Issue

• JDK-8215131: Pandoc 2.3/build documentation fixes

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk11u-dev pull/1314/head:pull/1314
$ git checkout pull/1314

Update a local copy of the PR:
$ git checkout pull/1314
$ git pull https://git.openjdk.org/jdk11u-dev pull/1314/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 1314

View PR using the GUI difftool:
$ git pr show -t 1314

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk11u-dev/pull/1314.diff

[bridgekeeper]

👋 Welcome back gdams! A progress list of the required criteria for merging this PR into pr/1313 will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

This backport pull request has now been updated with issue from the original commit.

[mlbridge]

Webrevs

• 00: Full (39f00766)

[gdams]

#1277