Update README.md

Rewrite as POSIX shell

See merge request cordelya/johnny-decimal!1

README.md

@@ -19,22 +19,19 @@ The markdown files are formatted such that they can be directly dumped into a Hu
     
 Setting your Pages site as "not public" is probably wise - don't give away OSINT for free!
 
-This script assumes that it lives inside a 00.xx directory. In other words, it's expecting to live at someplace like:
+This script will run in $PWD unless you optionally specify the root of your JD directory.
 
+You may also optionally specify the outfile, but if you choose to do this, you must specify the root of your JD directory.
 
+Usage:
+
+```sh
+build-index.sh [/path/to/JD/root] [/outfile/path/]
 ```
-├── 00-09 Index
-│   ├── 00 Index
-│   │   ├── 00.00 System
-│   │   ├── 00.01 Index
-│   │   └── 00.02 Index Scripts
-│   │  	    └── 00.02-build-index.sh
-```
-
-It should work as long as it lives three directories deep below the directory containing `00-09 Index` et seq., because it first asks "where do I live" and then "what's the absolute path of the directory three levels up from where I live?" So, it shouldn't matter which ID it's filed under.
-
-The script is set to ignore a directory named "System Volume Information" - an immediate solution to an immediate problem. A stretch goal is to change the script to only work with directories that match the naming convention patterns for each level. I did not have sufficient focus to be writing regex patterns when I initially wrote this script.
-
 ===
 
 You may contribute if you wish. Merge requests are welcomed. Don't be a jerk, &c &c.
+
+Contributors:
+
+- [Emma Tebibyte](https://gitlab.com/emmatebibyte)