[PD] Style the Pd html documentation

[abel.jerome at free.fr]

Some people try to write pd htlm documentation with a single file (pandoc) : https://github.com/pure-data/pure-data/pull/171

I would like to suggest to make it easier/pleasant to read, and design some css selectors + responsive layouts. A first step to see if you are interested to go further : http://reso-nance.org/public/pd-doc/

Here, I use a very nice and light css framework build by W3 (https://www.w3schools.com/w3css/).


Jérôme