Fix broken link for helm 3.0.0  (#109)

diff --git a/docs/.vuepress/config.js b/docs/.vuepress/config.js
index 193aa55..3297386 100755
--- a/docs/.vuepress/config.js
+++ b/docs/.vuepress/config.js
@@ -34,7 +34,7 @@
             { text: '6.5.0', link: "https://github.com/apache/skywalking/tree/v6.5.0/docs"},
             { text: 'Nginx LUA 0.1.0', link: "https://github.com/apache/skywalking-nginx-lua/tree/v0.1.0"},
             { text: 'CLI 0.3.0', link: "https://github.com/apache/skywalking-cli/tree/0.3.0"},
-            { text: 'Kubernetes helm 3.0.0', link: "https://github.com/apache/skywalking-kubernetes/tree/v3.1.0"},
+            { text: 'Kubernetes helm 3.0.0', link: "https://github.com/apache/skywalking-kubernetes/tree/v3.0.0"},
             { text: 'Kubernetes helm 2.0.0', link: "https://github.com/apache/skywalking-kubernetes/tree/v2.0.0"},
             { text: 'Python Agent 0.2.0', link: "https://github.com/apache/skywalking-python/tree/v0.2.0"},
           ], },
@@ -86,7 +86,7 @@
               { text: '6.5.0', link: "https://github.com/apache/skywalking/tree/v6.5.0/docs"},
               { text: 'Nginx LUA 0.1.0', link: "https://github.com/apache/skywalking-nginx-lua/tree/v0.1.0"},
               { text: 'CLI 0.3.0', link: "https://github.com/apache/skywalking-cli/tree/0.3.0"},
-              { text: 'Kubernetes helm 3.0.0', link: "https://github.com/apache/skywalking-kubernetes/tree/v3.1.0"},
+              { text: 'Kubernetes helm 3.0.0', link: "https://github.com/apache/skywalking-kubernetes/tree/v3.0.0"},
               { text: 'Kubernetes helm 2.0.0', link: "https://github.com/apache/skywalking-kubernetes/tree/v2.0.0"},
               { text: 'Python Agent 0.2.0', link: "https://github.com/apache/skywalking-python/tree/v0.2.0"},
             ],