Bump vue and vue-template-compiler in /src/docs

Bumps [vue](https://github.com/vuejs/vue) and [vue-template-compiler](https://github.com/vuejs/vue). These dependencies needed to be updated together.

Updates `vue` from 2.6.11 to 2.6.12
- [Release notes](https://github.com/vuejs/vue/releases)
- [Commits](vuejs/vue@v2.6.11...v2.6.12)

Updates `vue-template-compiler` from 2.6.11 to 2.6.12
- [Release notes](https://github.com/vuejs/vue/releases)
- [Commits](vuejs/vue@v2.6.11...v2.6.12)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

src/docs/package-lock.json

@@ -6,7 +6,7 @@
   ],
   "dependencies": {
     "register-service-worker": "^1.7.0",
-    "vue": "^2.6.11",
+    "vue": "^2.6.12",
     "vue-router": "^3.1.6"
   },
   "devDependencies": {
@@ -20,7 +20,7 @@
     "eslint": "^5.16.0",
     "node-sass": "^4.13.1",
     "sass-loader": "^7.3.1",
-    "vue-template-compiler": "^2.6.11"
+    "vue-template-compiler": "^2.6.12"
   },
   "eslintConfig": {
     "env": {