* implement initial add/remove fns

* add tests for add/remove fns

* implement remove functionality with tests

* update 'add' fn test

* update docs to include add/remove fns and remove docs:toc stage

* update index.html example

* update readme toc

* fix refactored docs

* refactor overlays property to be a getter fn

* refactor 'getOverlay' to 'get'

* update readme toc

* change example usage to use const instead of var

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Co-authored-by: uomar <uomar@brightcove.com>