Create README.md

gtests/net/packetdrill/contrib/README.md

+# Syntax Highlighting for packetdrill Scripts
+
+## BBEdit
+The file packetdrill.plist has to be copied into ~/Library/Application Support/BBEdit/Language Modules/.
+The extension .pkt for packetdrill scripts is recognized. Keywords and Predefined Names
+are colored. Numbers are colored from BBEdit 11.0 onwards.
+
+## Emacs
+Install packetdrill.el.
+
+## vim
+For installation the directories ~/.vim, ~/.vim/ftdetect and ~/.vim/syntax must exist.
+If they they don't exist, create them.
+Then create a file ~/.vim/ftdetect/packetdrill.vim with the contents:
+au BufRead,BufNewFile *.pkt set filetype=packetdrill
+Finally copy the provided file packetdrill.vim to ~/.vim/syntax/packetdrill.vim