Update README of chumpdetector with bazel build instructions.

Change-Id: I6e59c2b27c3caac84e12b1e3cdf7bff058cfeddd
Reviewed-on: https://chromium-review.googlesource.com/c/infra/gerrit-plugins/chumpdetector/+/1743009
Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
diff --git a/README.md b/README.md
index 21b12cd..8e2991f 100644
--- a/README.md
+++ b/README.md
@@ -82,10 +82,21 @@
 ## To use with the local testsite
 
 ```
-ln -s /path/to/chumpdetector-plugin plugins/chumpdetector
-NO_BUCKD=1 buck build plugins/chumpdetector && \
-  cp buck-out/gen/plugins/chumpdetector/chumpdetector.jar ../gerrit_testsite/plugins/ && \
-  ../gerrit_testsite/bin/gerrit.sh restart
+cd ~/gerrit
+ln -s ~/chumpdetector ~/gerrit/plugins
+bazel build //plugins/chumpdetector
+cp -f ~/gerrit/bazel-genfiles/plugins/chumpdetector/chumpdetector.jar ~/gerrit_testsite/plugins/
+bazel build gerrit
+java -jar ~/gerrit/bazel-bin/gerrit.war init --batch --dev -d ~/gerrit_testsite
+~/gerrit_testsite/bin/gerrit.sh start
+```
+
+When you make changes to chumpdetector
+
+```
+bazel build //plugins/chumpdetector
+cp -f ~/gerrit/bazel-genfiles/plugins/chumpdetector/chumpdetector.jar ~/gerrit_testsite/plugins/
+~/gerrit_testsite/bin/gerrit.sh restart
 ```
 
 ## To use with the polygerrit-ui server against live data