build/pkgs: Add some missing install-requires metadata, add some documentation to the developer's guide

[mkoeppe]

Dmitry Marakasov (repology.org) points out that some metadata are missing in our build/pkgs/.
repology/repology-updater#1118 (comment)

We fix this so that the SageMath distribution can be listed as a repository on repology.org

CC: @slel @dimpase @kiwifb @seblabbe @jhpalmieri @tobiasdiez

Component: build

Author: Matthias Koeppe

Branch/Commit: f829357

Reviewer: Dima Pasechnik

Issue created by migration from https://trac.sagemath.org/ticket/31321

[mkoeppe]

Branch: u/mkoeppe/build_pkgs__add_some_missing_metadata

[mkoeppe]

Commit: 5a92c51

[mkoeppe]

New commits:

18466f0	build/pkgs/wheel/install-requires.txt: New
8ec310e	src/doc/en/developer/packaging.rst: Explain install-requires.txt (from https://wiki.sagemath.org/ReleaseTours/sage-9.3)
5a92c51	build/pkgs/texttable/install-requires.txt: New

[mkoeppe]

comment:3

#29152 adds the missing upstream_url fields for rw, cliquer, meataxe.

[mkoeppe]

Author: Matthias Koeppe

[slel]

comment:6

Should there be a space between >= and the version number?

In one case there is no space, in the other there is one:

texttable >=1.6.3

wheel >= 0.36.2

Wondering whether this matters here.

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

52add22

build/pkgs/wheel/install-requires.txt: No space after >=

[sagetrac-git]

Changed commit from 5a92c51 to 52add22

[mkoeppe]

comment:8

Thanks for catching this, I want to standardize on the format without the space.

[mkoeppe]

comment:9

Needs review

[sagetrac-git]

Changed commit from 52add22 to f829357

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

f829357

Merge tag '9.3.beta7' into t/31321/build_pkgs__add_some_missing_metadata

[dimpase]

comment:11

lgtm

[dimpase]

Reviewer: Dima Pasechnik