Plugin Archetype: Add step to link watchmanconfig in Buck build docu

Change-Id: Id719338016acb68f7a92da39bcc9979d62f8229e
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>
diff --git a/gerrit-plugin-archetype/src/main/resources/archetype-resources/src/main/resources/Documentation/build.md b/gerrit-plugin-archetype/src/main/resources/archetype-resources/src/main/resources/Documentation/build.md
index 80f0627d..e4e944a 100644
--- a/gerrit-plugin-archetype/src/main/resources/archetype-resources/src/main/resources/Documentation/build.md
+++ b/gerrit-plugin-archetype/src/main/resources/archetype-resources/src/main/resources/Documentation/build.md
@@ -31,6 +31,11 @@
   cd @PLUGIN@ && ln -s bucklets/buckversion .buckversion
 ```
 
+Add link to the .watchmanconfig file:
+```
+  cd @PLUGIN@ && ln -s bucklets/watchmanconfig .watchmanconfig
+```
+
 To build the plugin, issue the following command: