Generic/TraitNameSuffix: add inline comment

This commit just adds an inline comment documenting why the sniff bails
early if there is no trait name. Doing this to follow the same pattern
used by other similar sniffs like AbstractClassName
https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/8a7ee56347bb4017ffc778a42a532cbb1651a20b/src/Standards/Generic/Sniffs/NamingConventions/AbstractClassNamePrefixSniff.php#L48

Author: rodrigoprimo

src/Standards/Generic/Sniffs/NamingConventions/TraitNameSuffixSniff.php

@@ -40,6 +40,7 @@ public function process(File $phpcsFile, $stackPtr)
     {
         $traitName = $phpcsFile->getDeclarationName($stackPtr);
         if ($traitName === null) {
+            // Live coding or parse error. Bow out.
             return;
         }