Improve README.md instructions.

Added instructions that would have made my initial attempts to use the tool less confusing.

README.md

@@ -22,13 +22,18 @@ based on [Leaflet](https://leafletjs.com/). The map renderer is heavily inspired
 
 ## How to use
 
+Download both the release that matches your platform, as well as the platform-
+independant viewer archive. Extract the viewer archive. This directory will be made
+publicly accessible on a web server and will contain both the html and javascript to
+operate the viewer, as well as the image data generated by MinedMap.
+
 Minecraft stores its save data in a directory `~/.minecraft/saves` on Linux,
 and `C:\Users\<username>\AppData\Roaming\.minecraft\saves`. To generate MinedMap
 tile data from a save game called "World", use the a command like the following
-(replacing the first argument with the path to your save data; `viewer` refers
+(replacing the first argument with the path to your save data; `<viewer>` refers
 to the directory where you unpacked the MinedMap viewer):
 ```shell
-minedmap ~/.minecraft/saves/World viewer/data
+minedmap ~/.minecraft/saves/World <viewer>/data
 ```
 
 The first map generation might take a while for big worlds, but subsequent calls will
@@ -47,6 +52,10 @@ This test server is very slow and cannot handle multiple requests concurrently,
 a proper webserver like [nginx](https://nginx.org/) or upload the viewer together with
 the generated map files to public webspace to make the map available to others.
 
+If you are uploading the directory to a remote webserver, you do not need to upload the 
+`<viewer>/data/processed` directory, as that is only used locally to make updates
+process more quickly.
+
 ### Signs
 
 ![Sign screenshot](https://raw.githubusercontent.com/neocturne/MinedMap/e5d9c813ba3118d04dc7e52e3dc6f48808a69120/docs/images/signs.png)