Clear description for max_version field

Currently max_version field shows text as
"Deprecated in version %s" which seems confusing to show
deprecated fields vs removed fields.

For example: if any element is removed in x version, then we
tag that element in parameter.yaml with max_version: x-1. api-ref shows
that element as "Deprecated in version x-1" which seems confusing on
below interpretation:
- is that element deprecated in x-1 version?
- is that element only deprecated in x-1 version not removed?

But actually that element is removed in x and only available till x-1 version.

- https://developer.openstack.org/api-ref/compute/?expanded=evacuate-server-evacuate-action-detail

This commit try to describe max_version filed in more clear way.

Change-Id: I388c6e27c3d15e3bee645b7b56f8142e2f16d3d6

doc/source/usage.rst

@@ -178,7 +178,7 @@ min_version
 
 max_version
   the last version that includes this parameter. Will render
-  a *Deprecated in $version* stanza in the html output.
+  a *Available until $version* stanza in the html output.
 
 
 rest_status_code

os_api_ref/__init__.py

@@ -441,7 +441,7 @@ class RestParametersDirective(Table):
                                         str(min_version).replace('.', '_'))
                     classes.append(min_ver_css_name)
                 if max_version:
-                    desc += ("\n\n**Deprecated in version %s**\n" %
+                    desc += ("\n\n**Available until version %s**\n" %
                              max_version)
                     max_ver_css_name = ("rp_max_ver_" +
                                         str(max_version).replace('.', '_'))

os_api_ref/tests/test_microversions.py

@@ -87,7 +87,7 @@ class TestMicroversions(base.TestCase):
 <td>body</td>
 <td>string</td>
 <td><p class="first">The name of things</p>
-<p class="last"><strong>Deprecated in version 2.20</strong></p>
+<p class="last"><strong>Available until version 2.20</strong></p>
 </td>
 </tr>
 </tbody>