Change docs layout

[siddharthlatest]

Change docs navbar layout to match visually with the kind of components.

Proposed new layout:

• [x] Getting Started
  • [x] Change components overview doc
• [x] ReactiveSearch Components
  • [x] Base
    • Base components
  • [x] List
    • List components
  • [x] Range
    • Range components
  • [x] Search
    • Search components
  • [x] Result
    • Result components
• [x] Theming
  • [x] Themes @metagrover
  • [x] How Styles Work @metagrover
  • [x] InnerClass @metagrover
• [x] Advanced
  • [x] React prop (Review, @siddharthlatest)
  • [x] customQuery (Review, @siddharthlatest)
  • [x] Indexing and Mapping guide #28 (@siddharthlatest)
  • [x] How to use events: onData, onAllData @siddharthlatest
  • [x] ReactiveComponent @metagrover
  • [ ] How to change props programmatically | Integrating your own React UI components
  • [x] How to use a middleware to secure all requests @siddharthlatest
  • [x] How to build a native app with ReactiveSearch
  • [x] Comparison: Searchkit, Instantsearch @siddharthlatest
• [x] ReactiveMaps Components

  Same arrangement as before

[siddharthlatest]

@metagrover See the docs you can update, I have already added stub content in all of them. (Note: They are in v2 branch)