Documentation: Add missing alternative for plugin in-tree testing

Bug: Issue 12096
Change-Id: I30949f8f89f3248384ec6df46f927555dfe70b64

src/main/resources/Documentation/build.md

diff --git a/src/main/resources/Documentation/build.md b/src/main/resources/Documentation/build.md
index b97861d..be769e2 100644
--- a/src/main/resources/Documentation/build.md
+++ b/src/main/resources/Documentation/build.md
@@ -92,7 +92,8 @@
 To execute the tests run:
 
 ```
-  bazel test plugins/@PLUGIN@:@PLUGIN@_tests 
+  bazel test --test_tag_filters=@PLUGIN@ //...
+  bazel test plugins/@PLUGIN@:@PLUGIN@_tests
 ```
 
 How to build the Gerrit Plugin API is described in the [Gerrit