Add a `FAQ` meta keyword to the frequently asked questions page

This makes it possible to find that page by simply searching "faq"
in the documentation search. Previously, no results would have been
returned.

about/faq.rst

@@ -1,3 +1,6 @@
+.. meta::
+    :keywords: FAQ
+
 .. _doc_faq:
 
 Frequently asked questions
@@ -309,7 +312,7 @@ executable.
 Why does Godot not enforce RTTI?
 --------------------------------
 
-Godot provides its own type-casting system, which can optionally use RTTI 
+Godot provides its own type-casting system, which can optionally use RTTI
 internally. Disabling RTTI in Godot means considerably smaller binary sizes can
 be achieved, at a little performance cost.
 
@@ -321,7 +324,7 @@ to use cache coherency as best as possible, we believe most users don't
 really need to be forced to use DoD practices.
 
 DoD is mostly a cache coherency optimization that can only gain you
-significant performance improvements when dealing with dozens of 
+significant performance improvements when dealing with dozens of
 thousands of objects (which are processed every frame with little
 modification). As in, if you are moving a few hundred sprites or enemies
 per frame, DoD won't help you, and you should consider a different approach