Update README

README.md

@@ -3,7 +3,6 @@
 
 Inspired by [Last.fm](https://last.fm), [Maloja](https://github.com/krateng/maloja), and [Lastfmstats.com](https://www.lastfmstats.com).
 
-
 **Z**uletzt is written with [**Z**ig](https://github.com/ziglang/zig) and [Jetzig](https://github.com/jetzig-framework/jetzig) as a means of learning the
 language, reintroducing myself to programming, and combining
 the functionality of the aforementioned inspirations.
@@ -12,6 +11,35 @@ Zuletzt means "last" in German.
 
 Licensed under MIT.
 
+## Usage 
+Zuletzt allows uploads of Scrobbles at the `/upload` page, where you
+can import Scrobbles from a Spotify data export, Last.FM data export (a `.json`
+file from lastfmstats.com), or by providing a Last.FM username and connecting
+to Last.FM directly.
+
+Zuletzt will not make any assumptions about the data, and only change metadata when asked to by a rule. Two albums will be considered the same if:
+- They share the same title (case/diacritic sensitive)
+- The album artist(s) are the same
+
+Zuletzt allows you to list multiple artists under an album using rules, but
+does not try to automatically split artists along common delimiters. For
+example, there's no way to know that "Mermaid Avenue" by "Billy Bragg, Wilco"
+is performed by two artists, while "Ants From Up There" by "Black Country, New
+Road" is performed by one artist. Thus, a rule needs to be made to tell Zuletzt
+"Mermaid Avenue" is performed by "Billy Bragg" and "Wilco".
+
+Two songs will only be considered the same if:
+- They share the same title (case/diacritic sensitive)
+- They appear on the same album
+
+If two or more songs with the same spelling appear on an album, they are
+necessarily grouped under the same name, as there is no way to differentiate
+them (see "Once In Royal David's City" on Sufjan Stevens's "Songs For
+Christmas", for example). Every artist that performs on those songs with
+receive attribution for the combined song.
+
+If two artists have the same name, they are necessarily listed as the same artist, but can be separated with a rule, or after the fact, with a disambiguation string.
+
 ## To-Do List:
 - [ ] Entity statistics
     - [x] See all artists under "/artists"
@@ -60,6 +88,7 @@ Licensed under MIT.
     - [ ] Rank songs
 - [ ] Custom statistics[^7]
 - [ ] "Playlists"[^8]
+- [ ] First launch setup
 
 [^1]: I do not intend to exactly replicate all the statistics Lastfmstats.com provides, but I would at least like to give the user the option to see those kinds of statistics, or generate them themselves (see 7).