Updating gitignore for generated plugins folder

Change-Id: I266db9f4667c4f720d6109fad5c4d31eb182ed30
Signed-off-by: Keith Burns (alagalah) <alagalah@gmail.com>
diff --git a/.gitignore b/.gitignore
index 689d009..b5673ae 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,6 +8,7 @@
 /build-root/packages-vpp/
 /build-root/path_setup
 /build-root/build-config.mk
+/build-root/deb/debian/vpp-plugins/
 /build-root/*.deb
 /build-root/*.rpm
 /build-root/*.changes