extlinks for Sage source files

[mkoeppe]

The documentation refers to various source files:

$ git grep -E "SAGE_ROOT/(build|src|pkgs)" src/doc
...
src/doc/en/developer/doctesting.rst:  * ``SAGE_ROOT/src/doc/en``
src/doc/en/developer/doctesting.rst:  * ``SAGE_ROOT/src/doc/fr``
src/doc/en/developer/packaging.rst:available packages are the subdirectories of ``SAGE_ROOT/build/pkgs/``.
src/doc/en/developer/packaging.rst:``SAGE_ROOT/build/bin/sage-spkg``. This script is typically invoked by
src/doc/en/developer/packaging.rst:of each individual package in ``SAGE_ROOT/build/pkgs``. In section
...

We create a new extlink format for it in src/sage/misc/sagedoc.py,

:sage_root:`src/doc/en`

which creates links to the corresponding file in https://github.com/sagemath/sage

CC: @kwankyu

Component: documentation

Author: Matthias Koeppe

Issue created by migration from https://trac.sagemath.org/ticket/33756

[mkoeppe]

Description changed:

--- 
+++ 
@@ -10,7 +10,7 @@
 src/doc/en/developer/packaging.rst:of each individual package in ``SAGE_ROOT/build/pkgs``. In section
 ...
 ```
-We create a new extlink format for it, 
+We create a new extlink format for it in `src/sage/misc/sagedoc.py`, 
 
 ```
 :sage_root:`src/doc/en`

[mkoeppe]

Branch: u/mkoeppe/extlinks_for_sage_source_files

[mkoeppe]

Author: Matthias Koeppe

[mkoeppe]

New commits:

3bcca8c	src/sage/misc/sagedoc.py: Add sage_root to extlinks
439145e	git grep -l -E "SAGE_ROOT/[^lu]" src/doc | xargs sed -i.bak 's,``SAGE_ROOT/\([^`]*\)``,:sage_root:`\1`,g'

[mkoeppe]

Commit: 439145e

[mkoeppe]

Removed branch from issue description; replaced by PR #37546