Fix order of of entries in CODEOWNERS

The last item has *most* precedence not *least*. Entries should be ordered the other way.

Author: ahoppen

.github/CODEOWNERS

@@ -7,13 +7,13 @@
 # Each line is a file pattern followed by one or more owners.
 # Order is important. The last matching pattern has the most precedence.
 
+# Owner of anything in SwiftSyntax not owned by anyone else.
+* @ahoppen
+
 # Macros
-Sources/_SwiftSyntaxMacros @DougGregor
-Tests/SwiftSyntaxMacrosTest @DougGregor
+/Sources/_SwiftSyntaxMacros @DougGregor
+/Tests/SwiftSyntaxMacrosTest @DougGregor
 
 # SwiftOperators
-Sources/SwiftOperators @DougGregor
-Tests/SwiftOperatorsTest @DougGregor
-
-# Owner of anything in SwiftSyntax not owned by anyone else.
-* @ahoppen
+/Sources/SwiftOperators @DougGregor
+/Tests/SwiftOperatorsTest @DougGregor