Encapsulate Microsoft page layout

Author: Bellangelo

_includes/namespace-entry.md

@@ -0,0 +1,11 @@
+# <a href="..">{{ page.collection }}</a>
+
+## {{ page.slug }} - {{ page.description }}
+
+{{ include.summary }}
+
+{% if page.issue %}
+### GitHub Issue
+
+* [#{{ page.issue }}](https://github.com/OAI/OpenAPI-Specification/issues/{{ page.issue }})
+{% endif %}

registries/_namespace/ms.md

@@ -5,15 +5,8 @@ description: Extensions created and used by Microsoft
 layout: default
 ---
 
-# <a href="..">{{ page.collection }}</a>
-
-## {{ page.slug }} - {{ page.description }}
-
-
+{% capture summary %}
 The `x-{{page.slug}}-` prefix is reserved for extensions created by Microsoft. These extensions are available for use by anyone.
+{% endcapture %}
 
-{% if page.issue %}
-### GitHub Issue
-
-* [#{{ page.issue }}](https://github.com/OAI/OpenAPI-Specification/issues/{{ page.issue }})
-{% endif %}
+{% include namespace-entry.md summary=summary %}