[doc] Provide an inventory of our environment variables

[jwnimmer-tri]

Towards #19044.

Amends #18819.

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This change is 

[jwnimmer-tri]

+@hongkai-dai for feature review of gurobi_solver.h please.

+@ggould-tri for feature review of the remainder & platform review per schedule, please.

[ggould-tri]

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: 3 unresolved discussions, LGTM missing from assignees ggould-tri(platform),hongkai-dai (waiting on @hongkai-dai and @jwnimmer-tri)

a discussion (no related file):
Is this the right place for the documentation? In our current implementation aiui this will not be linked or linkable from the pydrake docs. This might be better off in the Jekyll-based doc tree rather than in language-specific API docs.

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doc/doxygen_cxx/doxygen.h line 217 at r1 (raw file):

 @defgroup environment_variables Environment Variables

 This sections provides an inventory of environment variables relevant to Drake.

typo

Suggestion:

section

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doc/doxygen_cxx/doxygen.h line 217 at r1 (raw file):

 @defgroup environment_variables Environment Variables

 This sections provides an inventory of environment variables relevant to Drake.

minor: Alternatively, describe the content not the documentation?

Suggestion:

Drake and its solvers and visualizers use several environment variables:

[jwnimmer-tri]

Reviewable status: 1 unresolved discussion, LGTM missing from assignees ggould-tri(platform),hongkai-dai (waiting on @ggould-tri and @hongkai-dai)

a discussion (no related file):

Previously, ggould-tri wrote…

Is this the right place for the documentation? In our current implementation aiui this will not be linked or linkable from the pydrake docs. This might be better off in the Jekyll-based doc tree rather than in language-specific API docs.

If we wanted to make a hyperlink from pydrake API docs to here, it's no more difficult to link to doxygen than it is to jekyll. In either case, we just provide a (relative) URL; in neither case can we auto-link it with a short glyph.

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doc/doxygen_cxx/doxygen.h line 217 at r1 (raw file):

Previously, ggould-tri wrote…

minor: Alternatively, describe the content not the documentation?

That's a little better in situ, but I think worse in the https://drake.mit.edu/doxygen_cxx/group__technical__notes.html table of contents.

[ggould-tri]

Reviewed 1 of 1 files at r2, all commit messages.
Reviewable status: 1 unresolved discussion, LGTM missing from assignee hongkai-dai (waiting on @hongkai-dai)

[jwnimmer-tri]

Reviewable status: 1 unresolved discussion, LGTM missing from assignee hongkai-dai (waiting on @hongkai-dai and @jwnimmer-tri)

a discussion (no related file):
Working

I realized that we should mention OMP_NUM_THREADS in this list as well.

\CC @calderpg-tri FYI

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[jwnimmer-tri]

Reviewable status: LGTM missing from assignee hongkai-dai (waiting on @ggould-tri and @hongkai-dai)

a discussion (no related file):

Previously, jwnimmer-tri (Jeremy Nimmer) wrote…

Working

I realized that we should mention OMP_NUM_THREADS in this list as well.

\CC @calderpg-tri FYI

Done.

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[ggould-tri]

Reviewed 1 of 1 files at r3, all commit messages.
Reviewable status: LGTM missing from assignee hongkai-dai (waiting on @hongkai-dai)

[jwnimmer-tri]

To keep this moving, I'm extracting the Gurobi docs to a follow-up PR.

-@hongkai-dai +(status: single reviewer ok)