You will need to install a user script manager extension to install this script.
This script creates a Markdown toolbar whenever you make/edit text posts or comments in reddit.com.
This is a modified version of this script Markdown toolbar for GreasyFork and UserStyles.org.
Thanks a lot to wOxxOm for making that script.
The script works and is tested on Tampermonkey and Violentmonkey.
Greasemonkey -any version- is not supported (the script might work, but is not tested).
If you have any bugs, bug fixes or ideas, please report at my GitHub repo