add changelog to docs

CHANGELOG.rst

@@ -280,9 +280,11 @@ Please don't use this one.
 
 - Methods for getting time, population, and location information about individuals
   are now in tskit:
+
     * `SlimTreeSequence.individual_times` is now `TreeSequence.individuals_time()`
     * `SlimTreeSequence.individual_populations` is now `TreeSequence.individuals_population()`
     * `SlimTreeSequence.individual_locations` is now `TreeSequence.individuals_location()`
+
   However, this will be invisible to the user. In each case note the the
   location of the "s" has moved (to "individual*s* time" instead of "individual
   time*s*"), but the original version remains an undocumented alias.

docs/_toc.yml

@@ -21,4 +21,5 @@ parts:
   - file: python_api
 - caption: Miscellaneous
   chapters:
+  - file: changelogs
   - file: development

docs/changelogs.rst

@@ -0,0 +1,7 @@
+.. _sec_changelogs:
+
+==========
+Changelogs
+==========
+
+.. include:: ../CHANGELOG.rst