Add missing repo (#178)

diff --git a/data/docs.yml b/data/docs.yml
index 6a5d0b6..ee84e48 100644
--- a/data/docs.yml
+++ b/data/docs.yml
@@ -119,6 +119,14 @@
       user: apache
       repo: skywalking-query-protocol
 
+- type: Tools
+  description:
+  list:
+    - name: skywalking-agent-test-tool
+      icon: T
+      description: SkyWalking Agent Test Tool is a tremendously useful test tools suite in a wide variety of languages of Agent. Includes mock collector and validator.
+      user: apache
+      repo: skywalking-agent-test-tool
 
 - type: Ecosystem
   description: All following repositories are a part of SkyWalking ecosystem, as agent implementations, extensions, or tools. All the source codes and their distributions are not belonging to the Apache Software Foundation.