There is a real world alternative to Markdown. Ada programming language standard is defined in a text format that is converted to TXT, HTML and PDF. Tools can compare different Ada standard versions, sometimes several versions, producing multi colored documents.

Sources of standard: http://www.ada-auth.org/arm-files/2022-SRC.zip

Format tool can be found here: http://www.ada-auth.org/arm.html#Format_Tool

Sample output with edits: http://www.ada-auth.org/standards/22aarm/html/AA-5-2.html

Red color is for Ada 2012 -> Ada 2012 TC1 diff, green color is for Ada 2012 TC1 -> Ada 2022 diff.