Document milkshake a bit

components/milkshake/README.md

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+# Milkshake
+
+![milkshake](./milkshake.png)
+
+A tool for slurping S-expressions. They are quite tasty.
+
+## Grammar
+
+Milkshake supports a slightly expanded and idiosyncratic set of S-expression datums.
+Milkshake owes much to but is not quite Clojure's EDN.
+
+```lisp
+
+;; A comment. Any number of semicolons will do.
+
+()       ; A list
+'()      ; A quoted list
+[]       ; Another kind of list
+#[]      ; A vector (maybe just a list)
+{'foo 1} ; A mapping
+#{1 2 3} ; A set
+
+nil      ; A symbol
+/        ; Another symbol
+~        ; An unusual symbol
+#        ; Another unusual symbol
+
+/^\s+/   ; A regex pattern
+
+"foo"    ; A string
+
+1        ; A number
+1e3      ; Another number
++3.1415  ; Another form of a floating number
+1,000.00 ; A US-format number
+1.000,00 ; A more common number format
+1_000.00 ; A compromise form for a number
+
+`()      ; A quasiquoted expression
+`~()     ; An unqoted expression
+`~@()    ; A spliced expression
+```