Replace git.openstack.org URLs with opendev.org URLs.

Replace the old url by the new one in the README.rst file. Fix the title
format in several files.

Change-Id: I8777c0b9e09b91ae3ca89d562bf5fa2c24720616

README.rst

@@ -29,6 +29,6 @@ caching backends such as `Memcached <https://www.memcached.org/>`_.
 
 * Free software: Apache license
 * Documentation: https://docs.openstack.org/oslo.cache/latest/
-* Source: https://git.openstack.org/cgit/openstack/oslo.cache/
+* Source: https://opendev.org/openstack/oslo.cache/
 * Bugs: https://bugs.launchpad.net/oslo.cache
 * Release notes: https://docs.openstack.org/releasenotes/oslo.cache/

doc/source/configuration/index.rst

@@ -1,6 +1,6 @@
-=======================
- Configuration Options
-=======================
+=====================
+Configuration Options
+=====================
 
 oslo.cache uses oslo.config to define and manage configuration options
 to allow the deployer to control how an application uses this library.

doc/source/contributor/index.rst

@@ -1,5 +1,5 @@
-==============
- Contributing
-==============
+============
+Contributing
+============
 
 .. include:: ../../../CONTRIBUTING.rst

doc/source/index.rst

@@ -1,6 +1,6 @@
-============
- oslo.cache
-============
+==========
+oslo.cache
+==========
 
 Cache storage for OpenStack projects.
 

doc/source/install/index.rst

@@ -1,6 +1,6 @@
-==============
- Installation
-==============
+============
+Installation
+============
 
 At the command line::
 

doc/source/user/usage.rst

@@ -1,6 +1,6 @@
-=======
- Usage
-=======
+=====
+Usage
+=====
 
 A simple example of oslo.cache in use::