doc: document identify CLI

Depends on D3023

Test Plan

cd docs ; make

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Migrated from D3025 (view on Phabricator)

Build is green

Patch application report for D3025 (id=10743)

Rebasing onto 401bc17d...

Current branch diff-target is up to date.

Changes applied before test

commit 2ae347dce2415e5739283c36275ee9104d3d7e97
Author: Stefano Zacchiroli <zack@upsilon.cc>
Date:   Thu Apr 16 16:25:09 2020 +0200

    doc: document identify CLI

See https://jenkins.softwareheritage.org/job/DMOD/job/tests-on-diff/37/ for more details.

Merge request was merged

closed