CI: Add description to OSX deps build script

CI/util/build-package-deps-osx.sh

@@ -1,5 +1,11 @@
 #!/usr/bin/env bash
 
+# This script builds a tar file that contains a bunch of deps that OBS needs for
+# advanced functionality on OSX. Currently this tar file is pulled down off of s3
+# and used in the CI build process on travis.
+# Mostly this sets build flags to compile with older SDKS and make sure that 
+# the libs are portable.
+
 exists()
 {
   command -v "$1" >/dev/null 2>&1
@@ -149,4 +155,4 @@ cd $WORK_DIR
 
 tar -czf osx-deps.tar.gz obsdeps
 
-cp ./osx-deps.tar.gz $CURDIR
+cp ./osx-deps.tar.gz $CURDIR