Added documentation to the contributing file, and adjusted formatting of section headings.
Added documentation to the contributing file, and adjusted formatting of section headings.

williamcotton/bitcore,UdjinM6/bitcore-dash,pnagurny/bitcore,TeamPiggyCoin/PiggyCore,eordano/bitcore,bitjson/bitcore,jcvernaleo/bitcore,eordano/bitcore,adjoinant/bitcore,bilthon/bitcore,maraoz/coinforge,martindale/bitcore,bitjson/bitcore,jcvernaleo/bitcore,pnagurny/bitcore,bilthon/bitcore,initaldk/bitcore,martindale/bitcore,TeamPiggyCoin/PiggyCore,lekkas/bitcore,daxxog/clamcore,iobond/bitcore,MonetaryUnit/bitcore,bankonme/bitcore,GroestlCoin/groestlcore,eXcomm/bitcore,maraoz/coinforge,MonetaryUnit/bitcore,genecyber/bitcore,iobond/bitcore,eXcomm/bitcore,TOMOAKI12345/bitcore,bitpay/bitcore,initaldk/bitcore,janko33bd/bitcore,braydonf/bitcore,iobond/bitcore,bitpay/bitcore,phplaboratory/bitcore,TOMOAKI12345/bitcore,adjoinant/bitcore,bitpay/bitcore,genecyber/bitcore,iobond/bitcore,phplaboratory/bitcore,olalonde/bitcore,braydonf/bitcore,janko33bd/bitcore,martindale/bitcore,iobond/bitcore,bitjson/bitcore,litecoin-project/litecore,lekkas/bitcore,daxxog/clamcore,bitjson/bitcore,olalonde/bitcore,bitpay/bitcore,litecoin-project/litecore,martindale/bitcore,bankonme/bitcore,williamcotton/bitcore