Fix documentation for building elasticsearch module

Update steps in build.md documentation to correctly
build the index-elasticsearch module.

Bug: Issue 291524063
Release-Notes: skip
Change-Id: I5c9b03c078bc57c1c51a66d62ba65f1f97dfb9c1
diff --git a/src/main/resources/Documentation/build.md b/src/main/resources/Documentation/build.md
index acb8d85..b2a31c1 100644
--- a/src/main/resources/Documentation/build.md
+++ b/src/main/resources/Documentation/build.md
@@ -20,7 +20,7 @@
 git clone https://gerrit.googlesource.com/modules/index-elasticsearch
 cd gerrit/plugins
 ln -s ../../index-elasticsearch index-elasticsearch
-ln -sf ../../external_plugin_deps.bzl .
+ln -sf ../../index-elasticsearch/external_plugin_deps.bzl .
 ```
 
 From the Gerrit source tree issue the command `bazelisk build plugins/index-elasticsearch`.