Title pretty much sums it up. Are the rights given to adaptations granted if someone renders Markdown?
Usually not, usually
Translating literary works is generally regarded as an adaptation, but I don't think translation programs—and HTML and Markdown, two markup languages with similar principles—are adaptations. According to the description on Creative Commons,
Merely changing the format never creates a derivative.
So changing WAV to MP3 is not considered an adaptation, nor is changing DOC to PDF. As for HTML and Markdown, it seems a bit vague, but it can be said that although their encoding methods are different, the results presented are very similar.
a modification rises to the level of an adaptation under copyright law when the modified work is based on the prior work but manifests sufficient new creativity to be copyrightable
Adaptation produces a derivative. A derivative contains both the will of the original author and the adapter. Creation involves choice, the painter chooses the colors to use, and the translator chooses the words to translate. There are inherently fewer options to create a program. Rendering markdown to html can be done directly through other programs, and it is difficult to see the shadow of the adapter. Editorial originality is very import.
Yet one more thing is important: legal definitions. This is what it says in the https://creativecommons.org/faq/#what-is-an-adaptation FQA page
What constitutes an adaptation depends on applicable law
So, the laws of where you live still matter. We all know that there is a large gray area in copyright law, which often makes everything depend on the actual situation.
This is just a little bit of my personal thoughts for your reference :)
A clear answer is yes, MD was the original source, and it is modified to an entirely differentiated version of HTML. Under the definitions of the Creative Commons Attribution-ShareAlike 3.0 (CC BY-SA 3.0) adaptation is generally covered. Citing the legal code of the paper, adaptation is defined by Section 1 of Article a as:
"Adaptation" means a work based upon the Work, or upon the Work and other pre-existing works, such as a translation, adaptation, derivative work, arrangement of music or other alterations of a literary or artistic work, or phonogram or performance and includes cinematographic adaptations or any other form in which the Work may be recast, transformed, or adapted including in any form recognizably derived from the original, except that a work that constitutes a Collection will not be considered an Adaptation for the purpose of this License. For the avoidance of doubt, where the Work is a musical work, performance or phonogram, the synchronization of the Work in timed-relation with a moving image ("synching") will be considered an Adaptation for the purpose of this License.
From this, you have to note this instruction clearly:
or adapted including in any form recognizably derived from the original,
The output of the HTML seems that content is clearly derived from the original work does not mean it is not an adaptation. It is counted as an adaptation.
However, there are no exclusive rights granted, the adaptation is of similar content so using the same license and citing the original author is compulsory.