diff --git a/README.md b/README.md
index 50b686c..1ec91bc 100644
--- a/README.md
+++ b/README.md
@@ -7,3 +7,15 @@ necessary to set up a gentoo github mirror based sync system:
 * Updates the glsa directory.
 * Updates `herds.xml` file.
 * Updates the news directory.
+
+## Notes ##
+
+Note that typically most repositories other than `gentoo` don't come with a
+pregenerated cache. It is a good idea to generate/update their cache every
+time they are synced. One way to do this, is by activating the `example` hook
+script that portage installs by default in `/etc/portage/postsync.d`:
+
+```
+cp -i /etc/portage/repo.postsync.d/example /etc/portage/repo.postsync.d/gen_cache
+chmod +x /etc/portage/repo.postsync.d/gen_cache
+```