Add TODO list for channels
Add TODO list for channels

Known work still to be done.
ericstj/corefxlab,ahsonkhan/corefxlab,joshfree/corefxlab,whoisj/corefxlab,benaadams/corefxlab,VSadov/corefxlab,ericstj/corefxlab,dotnet/corefxlab,VSadov/corefxlab,joshfree/corefxlab,KrzysztofCwalina/corefxlab,Vedin/corefxlab,stephentoub/corefxlab,VSadov/corefxlab,ahsonkhan/corefxlab,ericstj/corefxlab,tarekgh/corefxlab,hanblee/corefxlab,Vedin/corefxlab,alexperovich/corefxlab,dotnet/corefxlab,KrzysztofCwalina/corefxlab,stephentoub/corefxlab,VSadov/corefxlab,benaadams/corefxlab,VSadov/corefxlab,Vedin/corefxlab,Vedin/corefxlab,Vedin/corefxlab,stephentoub/corefxlab,adamsitnik/corefxlab,ericstj/corefxlab,ericstj/corefxlab,whoisj/corefxlab,ericstj/corefxlab,stephentoub/corefxlab,VSadov/corefxlab,adamsitnik/corefxlab,stephentoub/corefxlab,tarekgh/corefxlab,Vedin/corefxlab,stephentoub/corefxlab,hanblee/corefxlab