first draft of Input

I propose merging it in this stage and iterating systematically with atomic pull requests. Otherwise please create alternative pull request with initial draft and we can iterate from that.

Input.md

+# vf:Input
+
+a slot which accepts resources going into the process
+
+## phases
+
+* Recipe - often containing broad description of acceptable resources
+* Plan - in this stage one can narrow further acceptable inputs from Recipe and serve as foundation to cast an Intent
+* Commitment - in this stage one has agreement for particular resource to bind with input slot
+* Event - stage after running the process which refers to resource actually put into input slot
+
+## verbs
+
+* use - for example a tool used in process
+* consume - for example an ingredient composed into the output