Is there a place where I can find the Bitcoin whitepaper by satoshi in plain text markdown format?
Perhaps convert the whitepaper in pdf to your required format?
A discussion in pandoc mentions
pdftohtml -xml to be most promising.
You can find a markdown version here.
I recently created a markdown version of the Bitcoin Whitepaper, which you can find at https://github.com/dhimmel/bitcoin-whitepaper/tree/master/content. Most of the markdown text is in this file. I based this version off the Whitepaper provided by the Satoshi Nakamoto Institute. Accordingly, the images are SVGs and the math is TeX-formatted.
The source markdown is compiled by the Manubot and served by GitHub pages at http://git.dhimmel.com/bitcoin-whitepaper/. Contributions are welcome if you notice any issues.
For the ODT-formatted whitepaper (in many languages) see https://github.com/saivann/bitcoinwhitepaper.
Update: See my Steemit post with more details on how I converted the whitepaper to markdown.