resources: Remove 'dist' from .gitignore. Add 'output'

Previously the binaries were built and moved to a directory called
'dist'. This has been renamed to 'output'. This commit updates the
.gitignore accordingly.

Change-Id: I87bbdca43534b4209a417a3993d09e27ae3f766d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-resources/+/28307
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: Bobby R. Bruce <bbruce@ucdavis.edu>
diff --git a/.gitignore b/.gitignore
index 1521c8b..53752db 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1 @@
-dist
+output