Consider it beta before it hits 1.0.0. It is undergoing major upgrades, as far as the time is found, in 2020 so let me know if anything is off.

For quick documentation see: https://github.com/kubaPod/M2MD/wiki

M2MD

Simple converter of Mathematica notebooks to markdown.

It originates from https://mathematica.stackexchange.com/q/84556/5478, it didn't evolve too much but I'm open to feedback as it is not something I use on daily basis.

Installation

Quick

ResourceFunction["GitHubInstall"][ "kubapod", "m2md" ]

Manual

Go to 'releases' tab and download appropriate .paclet file.

Run PacletInstall @ path/to/the.paclet file

Via MPM`

If you don't have MPM` yet, run:

Import["https://raw.githubusercontent.com/kubapod/mpm/master/install.m"]

and then:

Needs @ "MPM`"    
MPM`MPMInstall["kubapod", "m2md"]

From now on there should be a M2MD item in your Palettes menu.