message: docs: remove references to superset-ui-plugins
  `superset-ui-plugins` has been deprecated.[1] We now manages
  all basic visualizations in apache-superset/superset-ui .
  [1]
diff: @@ -88,9 +88,7 @@ little bit helps, and credit will always be given.
  - [Y Axis 2](#y-axis-2)
  - [Query](#query)
  - [Filters Configuration](#filters-configuration)
  - - [Options](#options)
  - [Chart Options](#chart-options)
  - - [X Axis](#x-axis)
  - [Y Axis](#y-axis)
  - [Other](#other)
  - [Unclassified](#unclassified)
  @@ -805,27 +803,29 @@ Then, [extract strings for the new language](#extracting-new-strings-for-transla
  ### Improving visualizations
  -Superset is working towards a plugin system where new visualizations can be installed as optional npm packages. To achieve this goal, we are not accepting pull requests for new community-contributed visualization types at the moment. However, bugfixes for current visualizations are welcome. To edit the frontend code for visualizations, you will have to check out a copy of [apache-superset/superset-ui-plugins](https://github.com/apache-superset/superset-ui-plugins):
  +Superset is working towards a plugin system where new visualizations can be installed as optional npm packages. To achieve this goal, we are not accepting pull requests for new community-contributed visualization types at the moment. However, bugfixes for current visualizations are welcome. To edit the frontend code for visualizations, you will have to check out a copy of [apache-superset/superset-ui](https://github.com/apache-superset/superset-ui):
  ```bash
  -git clone https://github.com/apache-superset/superset-ui-plugins.git
  -yarn && yarn build
  +git clone https://github.com/apache-superset/superset-ui.git
  +cd superset-ui
  +yarn
  +yarn build
  ```
  -Then use `npm link` to create a symlink of the source code in `superset-frontend/node_modules`:
  +Then use `npm link` to create symlinks of the plugins/superset-ui packages you want to edit in `superset-frontend/node_modules`:
  ```bash
  cd incubator-superset/superset-frontend
  -npm link ../../superset-ui-plugins/packages/superset-ui-[PLUGIN NAME]
  +npm link ../../superset-ui/plugins/[PLUGIN NAME]
  -# Or to link all plugin packages:
  -# npm link ../../superset-ui-plugins/packages/*
  +# Or to link all core superset-ui and plugin packages:
  +# npm link ../../superset-ui/{packages,plugins}/*
  # Start developing
  npm run dev-server
  ```
  -When plugin packages are linked with `npm link`, the dev server will automatically load files from the plugin's `/src` directory.
  +When `superset-ui` packages are linked with `npm link`, the dev server will automatically load a package's source code from its `/src` directory, instead of the built modules in `lib/` or `esm/`.
  Note that every time you do `npm install`, you will lose the symlink(s) and may have to run `npm link` again.
  