Distinct subdirectory in docs/README.md (#460)
Distinct subdirectory in docs/README.md (#460)

* Distinct subdirectory in docs/README.md

* keep subdirectory in alphabetical order

* add comment for directory control-plane & m4

p4lang/p4c,hanw/p4c,mbudiu-vmw/p4c-clone,p4lang/p4c,mbudiu-vmw/p4c-clone,p4lang/p4c,hanw/p4c,hanw/p4c,p4lang/p4c,p4lang/p4c,mbudiu-vmw/p4c-clone,mbudiu-vmw/p4c-clone,hanw/p4c