Remove old excludes
These are detected as errors since the clean up was done[1] in
the requirements repository.
[1] 314734e938f107cbd5ebcc7af4d9167c11347406
Also remove the note about old pip's behavior because the resolver
in recent pip no longer requires specific order.
Change-Id: Ic32aa7a18054c128efb9094154f055a2cf55c1f0
diff --git a/doc/requirements.txt b/doc/requirements.txt
index 6fe7c34..12d5b68 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -1,4 +1,4 @@
reno>=3.1.0 # Apache-2.0
-sphinx>=2.0.0,!=2.1.0 # BSD
+sphinx>=2.2.0 # BSD
openstackdocstheme>=2.2.1 # Apache-2.0