replace hardcoded urls to docs.pytest.org with internal crossrefs, add external crossrefs where possible

Signed-off-by: oleg.hoefling <oleg.hoefling@gmail.com>

doc/en/how-to/assert.rst

@@ -297,7 +297,7 @@ modules directly discovered by its test collection process, so **asserts in
 supporting modules which are not themselves test modules will not be rewritten**.
 
 You can manually enable assertion rewriting for an imported module by calling
-`register_assert_rewrite <https://docs.pytest.org/en/stable/how-to/writing_plugins.html#assertion-rewriting>`_
+:ref:`register_assert_rewrite <assertion-rewriting>`
 before you import it (a good place to do that is in your root ``conftest.py``).
 
 For further information, Benjamin Peterson wrote up `Behind the scenes of pytest's new assertion rewriting <http://pybites.blogspot.com/2011/07/behind-scenes-of-pytests-new-assertion.html>`_.

doc/en/how-to/cache.rst

@@ -383,6 +383,8 @@ servers where isolation and correctness is more important
 than speed.
 
 
+.. _cache stepwise:
+
 Stepwise
 --------
 

doc/en/how-to/capture-warnings.rst

@@ -172,7 +172,7 @@ DeprecationWarning and PendingDeprecationWarning
 
 
 By default pytest will display ``DeprecationWarning`` and ``PendingDeprecationWarning`` warnings from
-user code and third-party libraries, as recommended by `PEP-0565 <https://www.python.org/dev/peps/pep-0565>`_.
+user code and third-party libraries, as recommended by :pep:`565`.
 This helps users keep their code modern and avoid breakages when deprecated warnings are effectively removed.
 
 Sometimes it is useful to hide some specific deprecation warnings that happen in code that you have no control over
@@ -197,7 +197,7 @@ the regular expression ``".*U.*mode is deprecated"``.
     the :envvar:`python:PYTHONWARNINGS` environment variable or the
     ``-W`` command-line option, pytest will not configure any filters by default.
 
-    Also pytest doesn't follow ``PEP-0506`` suggestion of resetting all warning filters because
+    Also pytest doesn't follow :pep:`506` suggestion of resetting all warning filters because
     it might break test suites that configure warning filters themselves
     by calling :func:`warnings.simplefilter` (see issue `#2430 <https://github.com/pytest-dev/pytest/issues/2430>`_
     for an example of that).

doc/en/how-to/doctest.rst

@@ -92,6 +92,8 @@ that will be used for those doctest files using the
     [pytest]
     doctest_encoding = latin1
 
+.. _using doctest options:
+
 Using 'doctest' options
 -----------------------
 

doc/en/how-to/output.rst

@@ -3,6 +3,8 @@
 Managing pytest's output
 =========================
 
+.. _how-to-modifying-python-tb-printing:
+
 Modifying Python traceback printing
 --------------------------------------------------
 
@@ -466,8 +468,7 @@ by the `PyPy-test`_ web page to show test results over several revisions.
 
     If you use this option, consider using the new `pytest-reportlog <https://github.com/pytest-dev/pytest-reportlog>`__ plugin instead.
 
-    See `the deprecation docs <https://docs.pytest.org/en/stable/deprecations.html#result-log-result-log>`__
-    for more information.
+    See :ref:`the deprecation docs <resultlog deprecated>` for more information.
 
 
 .. _`PyPy-test`: http://buildbot.pypy.org/summary

doc/en/how-to/unittest.rst

@@ -27,7 +27,7 @@ Almost all ``unittest`` features are supported:
 * ``setUpClass/tearDownClass``;
 * ``setUpModule/tearDownModule``;
 
-.. _`load_tests protocol`: https://docs.python.org/3/library/how-to/unittest.html#load-tests-protocol
+.. _`load_tests protocol`: https://docs.python.org/3/library/unittest.html#load-tests-protocol
 
 Up to this point pytest does not have support for the following features: