Add: documentation for FileName sniff

WordPress/Docs/Files/FileNameStandard.xml

@@ -0,0 +1,32 @@
+<documentation title="File Name Standards">
+<standard>
+    <![CDATA[
+        Ensures that file names meet the following standards:
+        - Filenames should be all lowercase with hyphens separating words.
+        - Class file names should be based on the class name with "class-" prepended.
+        - Files in `wp-includes` containing template tags should end in `-template`.
+
+        If `$is_theme` property is set to `true` certain theme specific exceptions are made for underscores.
+    ]]>
+    </standard>
+    <code_comparison>
+        <code title="Valid: All lowercase with only hyphens as word separators and proper use of prefix/suffix.">
+        <![CDATA[
+echo taxonomy<em>-</em>my<em>-</em>term.inc
+echo <em>s</em>ome<em>f</em>ile.inc
+echo <em>class</em>-testsample.inc
+echo other<em>-</em>punctuation.inc
+echo general<em>-template</em>.php
+        ]]>
+        </code>
+        <code title="Invalid: Use of other punctuation, uppercase, or missing prefix/suffix.">
+        <![CDATA[
+echo taxonomy-my<em>_</em>term.inc.
+echo <em>S</em>ome<em>F</em>ile.inc
+echo <em>testsample</em>-unit-2.inc
+echo other<em>+</em>punctuation<em>#</em>.inc
+echo <em>general</em>.php
+        ]]>
+        </code>
+    </code_comparison>
+</documentation>