Update build documentation

chronicle-map has been moved from gerrithub to gerrit-review.

Update documentation with correct clone URLs and repository names.

Change-Id: I5eb0304a7be1e47af789a74f5b76779c6cf528bd
diff --git a/build.md b/build.md
index 3782de5..7e23698 100644
--- a/build.md
+++ b/build.md
@@ -12,9 +12,9 @@
 
 ```sh
 git clone https://gerrit.googlesource.com/gerrit
-git clone https://github.com/GerritForge/modules_cache-chroniclemap.git
+git clone https://gerrit.googlesource.com/modules/cache-chroniclemap
 cd gerrit/plugins
-ln -s ../../modules_cache-chroniclemap cache-chroniclemap
+ln -s ../../cache-chroniclemap cache-chroniclemap
 ln -sf ../../external_plugin_deps.bzl .
 ```