Test using c tag instead of code (#3628)

Author: mairaw

xml/Microsoft.Extensions.Http/PolicyHttpMessageHandler.xml

@@ -42,7 +42,7 @@
       <para>
             To adapt an existing non-generic <see cref="T:Polly.IAsyncPolicy" />, use code like the following:
             <example>
-            Converting a non-generic <code>IAsyncPolicy policy</code> to <see cref="T:Polly.IAsyncPolicy`1" />.
+            Converting a non-generic <c>IAsyncPolicy policy</c> to <see cref="T:Polly.IAsyncPolicy`1" />.
             <code>
             policy.AsAsyncPolicy&lt;HttpResponseMessage&gt;()
             </code></example></para>