page about robots.txt

Dear participants, 

I have added a page to the Github repo, which tries to summarize what is robots.txt and how it is used. Robots.txt has been described by Ivan Herman as a possible source of inspiration during our last call. 

https://github.com/w3c/tdm-reservation-protocol/blob/main/docs/robots.md <https://github.com/w3c/tdm-reservation-protocol/blob/main/docs/robots.md> 

Best regards
Laurent Le Meur