./bootstrap: Format build/pkgs/SPKG/distros/ information to produce the apt-get/yum command lines shown in the installation manual

[embray]

When trying to build Sage on a very bare fedora install (e.g. a Docker container) the packages listed in the build instructions at:

https://doc.sagemath.org/html/en/installation/source.html#linux-prerequisite-installation

are insufficient. At the very least it also needs findutils and which, and currently it also requires python2, though that should be fixed as part of #26953. The need for which comes, at the very least, from MPIR's configure script, which uses which at least on Linux.

With #29053, the necessary distribution packages for an installation are cataloged in build/pkgs/fedora.txt, build/pkgs/SPKG/distros/fedora.txt and similar for other distributions.

In this ticket, we add to bootstrap some code to keep the yum (and apt-get for debian) command-lines in the installation manual up to date. #29053 prepared this by isolating these command lines in separate .txt files in src/doc.

CC: @dimpase @embray @jhpalmieri

Component: documentation

Author: Matthias Koeppe

Branch: 688c68e

Reviewer: John Palmieri, Dima Pasechnik

Issue created by migration from https://trac.sagemath.org/ticket/26964

[embray]

comment:2

Retarging tickets optimistically to the next milestone. If you are responsible for this ticket (either its reporter or owner) and don't believe you are likely to complete this ticket before the next release (8.7) please retarget this ticket's milestone to sage-pending or sage-wishlist.

[embray]

comment:3

Removing most of the rest of my open tickets out of the 8.7 milestone, which should be closed.

[mkoeppe]

comment:4

Added these 2 packages to #29053.

[mkoeppe]

Dependencies: #29053

[mkoeppe]

Description changed:

--- 
+++ 
@@ -2,6 +2,10 @@
 
 https://doc.sagemath.org/html/en/installation/source.html#linux-prerequisite-installation
 
-are insufficient.  At the very least it also needs `findutils` and `which`, and currently it also requires `python2`, though that should be fixed as part of  #26953.
+are insufficient.  At the very least it also needs `findutils` and `which`, and currently it also requires `python2`, though that should be fixed as part of  #26953. The need for `which` comes, at the very least, from MPIR's `configure` script, which uses `which` at least on Linux.
 
-The need for `which` comes, at the very least, from MPIR's `configure` script, which uses `which` at least on Linux.
+With #29053, the necessary distribution packages for an installation are cataloged in `build/pkgs/fedora.txt`, `build/pkgs/SPKG/distros/fedora.txt` and similar for other distributions.
+
+In this ticket, we add to `bootstrap` some code to keep the `yum` (and `apt-get` for debian) command-lines in the  installation manual up to date. #29053 prepared this by isolating these command lines in separate .txt files in `src/doc`.
+
+

[mkoeppe]

Changed dependencies from #29053 to none