feat: add Pear's function missing docblock sniff.

This allows phpcs to error when a function is missing a docblock.

Author: yCodeTech

yCodeTech/ruleset.xml

@@ -100,4 +100,7 @@
 
     <!-- @param tag missing for the function parameter. -->
     <rule ref="Squiz.Commenting.FunctionComment.MissingParamTag"/>
+
+    <!-- Function docblock is missing. -->
+    <rule ref="PEAR.Commenting.FunctionComment.Missing"/>
 </ruleset>