Clarify what commenting *.pubxml does

https://github.com/github/gitignore/commit/08def965cd1c0241a7cffbe7c26a74b3cab61243 incorrect states that commenting *.pubxml will keep your passwords hidden when it will actually do the opposite. This clarifies what commenting *.pubxml does and warns you of the dangers.

VisualStudio.gitignore

@@ -125,7 +125,8 @@ publish/
 # Publish Web Output
 *.[Pp]ublish.xml
 *.azurePubxml
-# TODO: Comment out the next line if you want to keep your passwords hidden
+# TODO: Comment the next line if you want to checkin your
+# web deploy settings but any saved passwords will be unencrypted
 *.pubxml
 
 # NuGet Packages