doc: add pacman-contrib to optdeps in the README

We are depending on updpkgsums for the --update-checksums option used in
pkgctl build. Document this requirement.

Signed-off-by: Christian Heusel <christian@heusel.eu>

1 files changed, 1 insertions, 0 deletions

diff --git a/README.md b/README.md
index 3330fd3..193d5b0 100644
--- a/README.md
+++ b/README.md
@@ -91,6 +91,7 @@ Component: pkgctl db remove
 
 - bat (pretty printing)
 - nvchecker (version checking)
+- pacman-contrib (--update-checksums options for pkgctl build)
 
 ### Development Dependencies