Correct links to PEPs (#656)

Author: johnzhou721

content/contributing/process/contents.lr

@@ -127,7 +127,8 @@ Additional guidelines:
 - Use InitialCaps for class names (or for factory functions that return
   classes)
 
-- Use Sphinx-style docstrings and `257`; type annotation with `484` is
+- Use Sphinx-style docstrings and [PEP 257](https://peps.python.org/pep-0257/);
+  type annotation with [PEP 484](https://peps.python.org/pep-0484/) is
   optional but encouraged.
 
   For example:
@@ -153,8 +154,8 @@ Additional guidelines:
       def test_foo():
           """A test docstring looks like this (#123456)."""
 
-- Unless otherwise specified, follow `8` (with careful attention paid to
-  [Section
+- Unless otherwise specified, follow [PEP 8](https://peps.python.org/pep-0008/)
+  (with careful attention paid to [Section
   2](https://www.python.org/dev/peps/pep-0008/#a-foolish-consistency-is-the-hobgoblin-of-little-minds)).
 
 ---