Add some documentation

README.md

@@ -1,5 +1,58 @@
 # Nintendo parameter archive (AAMP) library
 
+Everything should work correctly for BotW parameter archives, though this hasn't been tested a lot.
+
+Some more esoteric parameter types are left unsupported currently.
+
+## Setup
+
+Install with `pip install aamp` or on Windows `py -m pip install aamp`.
+
+### Converter usage
+
+`aamp_to_yml` will convert an AAMP to a human readable representation.
+`yml_to_aamp` will do the opposite.
+
+### Library usage
+
+To read a parameter archive, create a Reader and give it the binary archive data,
+then call `parse()` to get a ParameterIO. This API is purposefully very similar to Nintendo's
+official parameter utils to help with reverse engineering and re-implementing parts of the game code.
+
+Parameter is a simple value, for example a boolean or an integer.
+
+ParameterObject is a key-value mapping where keys are strings and values are always Parameters.
+
+ParameterList is also a key-value mapping, but it contains objects and other lists rather than Parameters.
+
+ParameterIO is a special ParameterList with some extra attributes, like a version number and a type string (usually `xml`).
+
+```py
+>>> import aamp
+>>> reader = aamp.Reader(open('test_data/DamageReactionTable.bxml', 'rb').read())
+>>> pio = reader.parse()
+>>> pio.list('param_root').list('Basic').object('Edge')
+ParameterObject(params={375673178: True, 2982974660: True, 4022901097: True, 2861907126: True, 3947755327: True, 1529444359: False})
+>>> pio.list('param_root').list('Basic').object('Edge').param('Damage')
+True
+```
+
+ParameterObject:
+* `.param(param_name)` returns a parameter. KeyError is raised if the parameter doesn't exist.
+* `.set_param(param_name, value)`
+
+ParameterList:
+* `.list(list_name)` returns a parameter list. KeyError is raised if the list doesn't exist.
+* `.object(object_name)` returns a parameter object. KeyError is raised if the object doesn't exist.
+* `.set_list(list_name, param_list)`
+* `.set_object(object_name, param_object)`
+
+ParameterIO:
+* Same as ParameterList, but with extra attributes `version` (usually 0) and `type` (usually `xml`).
+
+For writing a binary parameter archive, create a Writer and pass it a ParameterIO,
+then call `write(stream)` with a seekable stream.
+
 ## License
 
 This software is licensed under the terms of the GNU General Public License, version 2 or later.