add brotli to main readme (#1661)
add brotli to main readme (#1661)


tarekgh/corefxlab,VSadov/corefxlab,joshfree/corefxlab,KrzysztofCwalina/corefxlab,VSadov/corefxlab,ahsonkhan/corefxlab,stephentoub/corefxlab,KrzysztofCwalina/corefxlab,stephentoub/corefxlab,whoisj/corefxlab,dotnet/corefxlab,stephentoub/corefxlab,VSadov/corefxlab,ericstj/corefxlab,benaadams/corefxlab,joshfree/corefxlab,ahsonkhan/corefxlab,benaadams/corefxlab,dotnet/corefxlab,VSadov/corefxlab,stephentoub/corefxlab,adamsitnik/corefxlab,tarekgh/corefxlab,stephentoub/corefxlab,ericstj/corefxlab,ericstj/corefxlab,VSadov/corefxlab,adamsitnik/corefxlab,ericstj/corefxlab,ericstj/corefxlab,stephentoub/corefxlab,whoisj/corefxlab,VSadov/corefxlab,ericstj/corefxlab