Add installation and usage to readme, plus other updates

README.md

@@ -3,13 +3,78 @@
 Command line interface and library for DMs and other players of Advanced
 Dungeons & Dragons (AD&D).
 
-**This project is BRAND NEW and TOTALLY INCOMPLETE. I am completely new to Rust
-and I don't recommend using this project yet.**
+**This project is BRAND NEW and TOTALLY INCOMPLETE.** I am completely new to
+Rust and this is quite light on tests. I use it for my game, but there is a lot
+of room for improvement. You have been warned.
 
 This tool is for **original, by the book AD&D**, though it might be useful
 for other versions of D&D. For more information about the kind of AD&D
 dmn is meant for, see https://demonidol.com.
 
+## Installation
+
+```
+cargo install dmn
+```
+
+If you don't know what cargo is, just [email me](mailto:eapoems@riseup.net) for
+now and I'll send you the program. I'll make the program more-easily available
+soon.
+
+## Usage
+
+dmn is really light on features right now, but it can do some useful things
+that can save you quite a lot of time during prep or even at the table. I hope
+to make these more useful as time goes on.
+
+Show help:
+
+```shell
+dmn help
+```
+
+Roll some dice (only supports XdY and dY format so far):
+
+```shell
+dmn roll 4d6
+```
+
+Generate a random magic item (includes 10% chance for a map, and uses *[Heroic
+Legendarium](https://preview.drivethrurpg.com/en/product/357539/The-Heroic-Legendarium-A-First-Edition-Adventure-Gaming-Companion)*
+chances for katanas and such):
+
+```shell
+dmn random magic
+```
+
+Generate a random henchman (does not yet properly limit classes or races by
+ability scores, nor classes by race or alignment):
+
+```shell
+dmn random henchman
+```
+
+Get the henchman in CSV format so you can copy and paste right into a
+spreadsheet:
+
+```shell
+dmn random henchman --csv
+```
+
+Generate 30 henchmen in CSV format (`repeat` only works in zsh; for bash or
+whatever you'll need to use a `for` loop or something):
+
+```shell
+repeat 30 { dmn random henchman --csv }
+```
+
+Roll on a specific table (available tables can be seen by looking in the files
+in `src/data/random_tables`):
+
+```shell
+dmn table hl_non_magic
+```
+
 ## Hacking
 
 This is my first Rust project. I haven't even finished reading the Rust book