Add CHANGELOG to the docs

This uses a cheesy trampoline file, but it seems to work alright.

doc_src/CHANGELOG.rst

@@ -0,0 +1,4 @@
+CHANGELOG
+#########
+
+.. include:: ../CHANGELOG.rst

doc_src/conf.py

@@ -191,6 +191,7 @@ def get_command_description(path, name):
 man_pages = [
     (master_doc, "fish-doc", "fish-shell Documentation", [author], 1),
     ("tutorial", "fish-tutorial", "fish-shell tutorial", [author], 1),
+    ("CHANGELOG", "fish-changelog", "fish-shell changelog", [author], 1),
     ("completions", "fish-completions", "Writing fish completions", [author], 1),
     ("faq", "fish-faq", "fish-shell faq", [author], 1),
 ]

doc_src/index.rst

@@ -1878,3 +1878,4 @@ Other help pages
    completions
    faq
    license
+   CHANGELOG