docs: add usage docs to the readme

Author: jtpavlock

README.rst

@@ -5,4 +5,58 @@ Moe is our resident Music-Organizer-Extraordinaire who's sole purpose is to give
 
 In short, Moe maintains a database of your music library that can be updated with various metadata sources, queried, edited, etc. through either an API or command-line interface. All of these features, and more, are made available by a highly extensible plugin ecosystem.
 
+Usage
+=====
+Moe comes with a command-line interface which is how most users will take advantage of the library management features. Below is a screenshot of Moe importing an album from the filesystem and adding it to the underlying database all while fixing tags, relocating the files, and anything else you can imagine.
+
+.. image:: _static/import_example.png
+
+Alternatively, because all the core functionality is available via an API, the underlying music management system can be incorporated into any existing program or other user interface.
+
+Finally, although a lot of Moe's functionality exists around the idea of operating on a library database of your music, the database is entirely optional. In this case, Moe provides a convenient set of tools and functionality for handling music in a general sense. For example, below is a standalone python script that takes an album directory and Musicbrainz release ID from the command-line, and then updates the underlying files' tags with any changes from Musicbrainz.
+
+.. code:: python
+
+    #!/usr/bin/env python3
+
+    import argparse
+    import pathlib
+
+    import moe.plugins.musicbrainz as moe_mb
+    from moe.config import Config, ConfigValidationError
+    from moe.library import Album
+    from moe.plugins.write import write_tags
+
+
+    def main():
+        try:
+            Config(init_db=False)
+        except ConfigValidationError as err:
+            raise SystemExit(1) from err
+
+        parser = argparse.ArgumentParser(
+            description="Update an album with musicbrainz tags."
+        )
+        parser.add_argument("path", help="dir of the album to update")
+        parser.add_argument("mb_id", help="musicbrainz id of the album to fetch")
+        args = parser.parse_args()
+
+        album = Album.from_dir(pathlib.Path(args.path))
+
+        album.merge(moe_mb.get_album_by_id(args.mb_id), overwrite=True)
+
+        for track in album.tracks:
+            write_tags(track)
+
+
+    if __name__ == "__main__":
+        main()
+
+.. note::
+
+   Notice the use of ``init_db=False`` when initializing the configuration to tell Moe you don't want to use or create a database file.
+
+
+This is just a small taste of what Moe is capable of and how it can make your life easier when dealing with music in Python. Stop re-inventing the wheel; use Moe.
+
 If you want to learn more, check out the `Getting Started <https://mrmoe.readthedocs.io/en/latest/getting_started.html>`_ docs.