Documentation: Fix plugin testing for standalone and in-tree

Add alternative for plugin in-tree testing and replace standalone with
standard way of running bazel test.

Bug: Issue 12096
Change-Id: I469dd0270b8dabd917a3607d22cb5daf8c9f32bc

src/main/resources/Documentation/build.md

diff --git a/src/main/resources/Documentation/build.md b/src/main/resources/Documentation/build.md
index c2d0532..6382d72 100644
--- a/src/main/resources/Documentation/build.md
+++ b/src/main/resources/Documentation/build.md
@@ -22,7 +22,7 @@
 To execute the tests run:
 
 ```
-  bazel test :@PLUGIN@_tests
+  bazel test //...
 ```
 
 ### Build in Gerrit tree
@@ -56,9 +56,10 @@
   ./tools/eclipse/project.py
 ```
 
-To execute the tests run:
+To execute the tests run either one of:
 
 ```
+  bazel test --test_tag_filters=@PLUGIN@ //...
   bazel test plugins/@PLUGIN@:@PLUGIN@_tests
 ```