Repository: pypa/pip

Issue:
restore a broken slug anchor in user guide
ping @uranusjr , @di 


Discussion:
[Rendered preview](https://pip--8781.org.readthedocs.build/en/8781/user_guide/#using-pip-from-your-program) to confirm the anchor is fixed.

Test failures are unrelated, caused by availability issues of http://svn.colorstudy.com.

Can you add a `8781.doc` news fragment to describe this change?
LGTM after add news 
Linting error is

```
Warning, treated as error:
docs/html/installing.rst:40:term not in glossary: pypug:source distribution (or "sdist")
ERROR: InvocationError for command .tox/docs/bin/sphinx-build -W -d .tox/docs/tmp/doctrees/html -b html docs/html docs/build/html (exited with code 2)
```

Seems unrelated? But why does master not fail?
> Linting error is
> 
> ```
> Warning, treated as error:
> docs/html/installing.rst:40:term not in glossary: pypug:source distribution (or "sdist")
> ERROR: InvocationError for command .tox/docs/bin/sphinx-build -W -d .tox/docs/tmp/doctrees/html -b html docs/html docs/build/html (exited with code 2)
> ```
> 
> Seems unrelated? But why does master not fail?

hmm weird, what about re run?

Same here: https://github.com/pypa/pip/pull/8771

@uranusjr I can reproduce the error locally. I'm not expert with sphinx but seems that the reference to https://github.com/pypa/packaging.python.org/blame/master/source/glossary.rst#L209 is not successfully.

```
/home/eamanu/dev/pip/.tox/docs/bin/sphinx-build -W -d /home/eamanu/dev/pip/.tox/docs/tmp/doctrees/html -b html docs/html docs/build/html
Running Sphinx v2.4.3
20.3
loading intersphinx inventory from https://packaging.python.org/objects.inv...
loading intersphinx inventory from https://www.pypa.io/en/latest/objects.inv...
building [mo]: targets for 0 po files that are out of date
building [html]: targets for 39 source files that are out of date
updating environment: [new config] 39 added, 0 changed, 0 removed
reading sources... [100%] user_guide                                                                                                                                                                                                                                                                                         
looking for now-outdated files... none found
pickling environment... done
checking consistency... done
preparing documents... done
writing output... [100%] user_guide                                                                                                                                                                                                                                                                                          

Warning, treated as error:
/home/eamanu/dev/pip/docs/html/installing.rst:40:term not in glossary: pypug:source distribution (or "sdist")

```

IMO  there is some new on sphinx that break that behaviour. But again, I'm not expert and I don't have evidences of the problem.

Tomorrow I can continue looking that


It's case-sensitive now, IIUC -- maybe that's why?
https://travis-ci.com/github/pypa/pip/jobs/375534050 -- looks like master is failing as well.

Resolving patch:
diff --git a/docs/html/conf.py b/docs/html/conf.py
--- a/docs/html/conf.py
+++ b/docs/html/conf.py
@@ -143,7 +143,9 @@
     'collapsiblesidebar': True,
     'externalrefs': True,
     'navigation_depth': 3,
-    'issues_url': 'https://github.com/pypa/pip/issues'
+    'issues_url': 'https://github.com/pypa/pip/issues',
+    'codebgcolor': '#eeffcc',
+    'codetextcolor': '#333333',
 }
 
 # Add any paths that contain custom themes here, relative to this directory.


Test patch: