Add instructions for implementing cowsay (#11)

This is for sprint 4

Author: illicitonion

implement-cowsay/README.md

@@ -0,0 +1,59 @@
+# Implement cowsay
+
+Your task is to write a command line tool which uses the `cowsay` library to show user-supplied text, as said by a specified animal.
+
+You must use the cowsay library, and you must not write down the list of supported animals yourself - you must fetch this information from the library.
+
+The following command lines should work as demonstrated below:
+
+```console
+% python3 cow.py Grass, delicious.
+  _________________
+| Grass, delicious. |
+  =================
+                 \
+                  \
+                    ^__^
+                    (oo)\_______
+                    (__)\       )\/\
+                        ||----w |
+                        ||     ||
+% python3 cow.py --animal turtle Fish are cool!
+  ______________
+| Fish are cool! |
+  ==============
+                \
+                 \
+                  \
+                   \
+                                              ___-------___
+                                          _-~~             ~~-_
+                                       _-~                    /~-_
+                     /^\__/^\         /~  \                   /    \
+                   /|  O|| O|        /      \_______________/        \
+                  | |___||__|      /       /                \          \
+                  |          \    /      /                    \          \
+                  |   (_______) /______/                        \_________ \
+                  |         / /         \                      /            \
+                   \         \^\\         \                  /               \     /
+                     \         ||           \______________/      _-_       //\__//
+                       \       ||------_-~~-_ ------------- \ --/~   ~\    || __/
+                         ~-----||====/~     |==================|       |/~~~~~
+                          (_(__/  ./     /                    \_\      \.
+                                 (_(___/                         \_____)_)
+% python3 cow.py --animal fish Turtles are cool too!
+usage: cowsay [-h] [--animal {beavis,cheese,cow,daemon,dragon,fox,ghostbusters,kitty,meow,miki,milk,octopus,pig,stegosaurus,stimpy,trex,turkey,turtle,tux}] message [message ...]
+cowsay: error: argument --animal: invalid choice: 'fish' (choose from 'beavis', 'cheese', 'cow', 'daemon', 'dragon', 'fox', 'ghostbusters', 'kitty', 'meow', 'miki', 'milk', 'octopus', 'pig', 'stegosaurus', 'stimpy', 'trex', 'turkey', 'turtle', 'tux')
+% python3 cow.py --help
+usage: cowsay [-h] [--animal {beavis,cheese,cow,daemon,dragon,fox,ghostbusters,kitty,meow,miki,milk,octopus,pig,stegosaurus,stimpy,trex,turkey,turtle,tux}] message [message ...]
+
+Make animals say things
+
+positional arguments:
+  message               The message to say.
+
+options:
+  -h, --help            show this help message and exit
+  --animal {beavis,cheese,cow,daemon,dragon,fox,ghostbusters,kitty,meow,miki,milk,octopus,pig,stegosaurus,stimpy,trex,turkey,turtle,tux}
+                        The animal to be saying things.
+```