0.0.3

- [X] Update an existing TOC
  - [X] Create a section around TOC
  - [X] Find if a TOC is already present in buffer
  - [X] Remove old TOC
  - [X] Create new one
- [X] Reference markdown-toc version
- [X] Reference the inspiration from doctoc
- [X] Upgrade version
- [X] Release notes