Add citation to cc.pretty

ust to look extra pretentious.

src/main/resources/data/computercraft/lua/rom/modules/main/cc/pretty.lua

@@ -1,23 +1,28 @@
---- Provides a "pretty printer", for rendering data structures in an
--- aesthetically pleasing manner.
---
--- In order to display something using @{cc.pretty}, you build up a series of
--- @{Doc|documents}. These behave a little bit like strings; you can concatenate
--- them together and then print them to the screen.
---
--- However, documents also allow you to control how they should be printed. There
--- are several functions (such as @{nest} and @{group}) which allow you to control
--- the "layout" of the document. When you come to display the document, the 'best'
--- (most compact) layout is used.
---
--- @module cc.pretty
--- @usage Print a table to the terminal
---     local pretty = require "cc.pretty"
---     pretty.print(pretty.pretty({ 1, 2, 3 }))
---
--- @usage Build a custom document and display it
---     local pretty = require "cc.pretty"
---     pretty.print(pretty.group(pretty.text("hello") .. pretty.space_line .. pretty.text("world")))
+--[[- Provides a "pretty printer", for rendering data structures in an
+aesthetically pleasing manner.
+
+In order to display something using @{cc.pretty}, you build up a series of
+@{Doc|documents}. These behave a little bit like strings; you can concatenate
+them together and then print them to the screen.
+
+However, documents also allow you to control how they should be printed. There
+are several functions (such as @{nest} and @{group}) which allow you to control
+the "layout" of the document. When you come to display the document, the 'best'
+(most compact) layout is used.
+
+The structure of this module is based on [A Prettier Printer][prettier].
+
+[prettier]: https://homepages.inf.ed.ac.uk/wadler/papers/prettier/prettier.pdf "A Prettier Printer"
+
+@module cc.pretty
+@usage Print a table to the terminal
+    local pretty = require "cc.pretty"
+    pretty.print(pretty.pretty({ 1, 2, 3 }))
+
+@usage Build a custom document and display it
+    local pretty = require "cc.pretty"
+    pretty.print(pretty.group(pretty.text("hello") .. pretty.space_line .. pretty.text("world")))
+]]
 
 local expect = require "cc.expect"
 local expect, field = expect.expect, expect.field