Remove style guide recommendation on global base components

Right now official Vue Style Guide suggests you use global components when you deal with base components. This can lead to confusion with new developers coming to a project, IDE assistance and testing. This PR removes this recommendation so it's always obvious how components are imported.

Author: CyberAP

src/v2/style-guide/index.md

@@ -771,22 +771,6 @@ Some advantages of this convention:
 
 - Since component names should always be multi-word, this convention prevents you from having to choose an arbitrary prefix for simple component wrappers (e.g. `MyButton`, `VueButton`).
 
-- Since these components are so frequently used, you may want to simply make them global instead of importing them everywhere. A prefix makes this possible with Webpack:
-
-  ``` js
-  var requireComponent = require.context("./src", true, /Base[A-Z]\w+\.(vue|js)$/)
-  requireComponent.keys().forEach(function (fileName) {
-    var baseComponentConfig = requireComponent(fileName)
-    baseComponentConfig = baseComponentConfig.default || baseComponentConfig
-    var baseComponentName = baseComponentConfig.name || (
-      fileName
-        .replace(/^.+\//, '')
-        .replace(/\.\w+$/, '')
-    )
-    Vue.component(baseComponentName, baseComponentConfig)
-  })
-  ```
-
 {% raw %}</details>{% endraw %}
 
 {% raw %}<div class="style-example example-bad">{% endraw %}