Fix Xojo.gitignore exclusion of Builds folder

- The “Builds” folder pattern would match source code files starting
with “Builds”. Corrected to only match directories with Xojo’s
Builds folder naming convention.
- Removed blank line between comment heading and patterns

Xojo.gitignore

@@ -1,6 +1,5 @@
 # Xojo (formerly REALbasic and Real Studio)
-
-Builds*
+Builds - */
 *.debug
 *.debug.app
 Debug*.exe