chore: add some comments and docs

Author: nlf

Diff for: README.md

@@ -147,3 +147,14 @@ Functionally, this means:
   hook scripts, then they can override the default package script with an
   explicit `cmd` option pointing to the `node_modules/.hook/${event}`
   script.
+
+## Escaping
+
+In order to ensure that arguments are handled consistently, this module
+writes a temporary script file containing the command as it exists in
+the package.json, followed by the user supplied arguments having been
+escaped to ensure they are processed as literal strings. We then instruct
+the shell to execute the script file, and when the process exits we remove
+the temporary file.
+
+The actual implementation of the escaping is in `lib/escape.js`.

Diff for: lib/escape.js

@@ -1,5 +1,7 @@
 'use strict'
 
+// eslint-disable-next-line max-len
+// this code adapted from: https://blogs.msdn.microsoft.com/twistylittlepassagesallalike/2011/04/23/everyone-quotes-command-line-arguments-the-wrong-way/
 const cmd = (input) => {
   if (!input.length) {
     return '""'