Add leaflet marker icon gotcha's to the docs

[DonNicoJs]

see #28

[dreamid27]

how I contribute? in the readme section, I don't see about how to contribute, pull request method, and all about the branch

[DonNicoJs]

@dreamid27 you can check the related issue linked in the description and sunmarize all the quirks in a docs pr either in faq or under the marker component

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[yog3sha]

How to write 'delete L.Icon.Default.prototype._getIconUrl;'
without getting error 'Property '_getIconUrl' does not exist on type 'Default'.'
in the console? Am I the only one using Typescript?