src/doc/en/developer: Replace outdated link to https://www.sagemath.org/links-components.html by ref to spkg chapter

Author: Matthias Koeppe

src/doc/en/developer/coding_basics.rst

@@ -7,10 +7,10 @@ General Conventions
 ===================
 
 
-There are many ways to contribute to Sage including sharing scripts
-and Sage worksheets that implement new functionality using Sage,
+There are many ways to contribute to Sage, including sharing scripts
+and Jupyter notebooks that implement new functionality using Sage,
 improving to the Sage library, or to working on the many underlying
-libraries distributed with Sage [1]_.
+libraries distributed with Sage, see :ref:`spkg`.
 This guide focuses on editing the Sage library itself.
 
 Sage is not just about gathering together functionality. It is about
@@ -20,10 +20,6 @@ mathematically. In the design of Sage, the semantics of objects, the
 definitions, etc., are informed by how the corresponding objects are
 used in everyday mathematics.
 
-.. [1]
-   See https://www.sagemath.org/links-components.html for a full list
-   of packages shipped with every copy of Sage
-
 To meet the goal of making Sage easy to read, maintain, and improve,
 all Python/Cython code that is included with Sage should adhere to the
 style conventions discussed in this chapter.

src/doc/en/developer/coding_in_other.rst

@@ -8,9 +8,9 @@ When writing code for Sage, use Python for the basic structure and
 interface. For speed, efficiency, or convenience, you can implement
 parts of the code using any of the following languages: :ref:`Cython
 <chapter-cython>`, C/C++, Fortran 95, GAP, Common Lisp, Singular, and
-PARI/GP. You can also use all C/C++ libraries included with Sage
-[SageComponents]_. And if you are okay with your code depending on
-optional Sage packages, you can use Octave, or even Magma,
+PARI/GP. You can also use all C/C++ libraries included with Sage,
+see :ref:`spkg`. And if you are okay with your code depending on
+external programs, you can use Octave, or even Magma,
 Mathematica, or Maple.
 
 In this chapter, we discuss interfaces between Sage and :ref:`PARI
@@ -753,7 +753,3 @@ These are only excerpts from ``octave.py``; check that file for more
 definitions and examples. Look at other files in the directory
 ``SAGE_ROOT/src/sage/interfaces/`` for examples of interfaces to other
 software packages.
-
-
-.. [SageComponents] See http://www.sagemath.org/links-components.html
-   for a list