docs: minor improvements to the migrating page

Author: nedbat

doc/migrating.rst

@@ -7,26 +7,31 @@
 Migrating between versions
 ==========================
 
-New major versions of coverage.py might require you to adjust your settings,
-options, or other aspects of your use.  This page details those changes.
+New versions of coverage.py or Python might require you to adjust your
+settings, options, or other aspects how you use coverage.py.  This page details
+those changes.
 
-.. _migrating_6x_7x:
+.. _migrating_cov7:
 
-Migrating from 6.x to 7.x
--------------------------
+Migrating to coverage.py 7.x
+----------------------------
 
-- The way that wildcards when specifying file paths work in certain cases has changed in 7.x:
+Consider these changes when migrating to coverage.py 7.x:
+
+- The way that wildcards when specifying file paths work in certain cases has
+  changed in 7.x:
 
   - Previously, ``*`` would incorrectly match directory separators, making
     precise matching difficult. Patterns such as ``*tests/*``
     will need to be changed to ``*/tests/*``.
 
-  - ``**`` now matches any number of nested directories. If you wish to retain the behavior of
-    ``**/tests/*`` in previous versions then  ``*/**/tests/*`` can be used instead.
+  - ``**`` now matches any number of nested directories. If you wish to retain
+    the behavior of ``**/tests/*`` in previous versions then  ``*/**/tests/*``
+    can be used instead.
 
 - When remapping file paths with ``[paths]``, a path will be remapped only if
-  the resulting path exists. Ensure that remapped ``[paths]`` exist when upgrading
-  as this is now being enforced.
+  the resulting path exists. Ensure that remapped ``[paths]`` exist when
+  upgrading as this is now being enforced.
 
 - The :ref:`config_report_exclude_also` setting is new in 7.2.0.  It adds
   exclusion regexes while keeping the default built-in set. It's better than