added installation and usage instructions to readme

README.md

@@ -3,3 +3,18 @@ A set of mods for Minetest for generating fractal worlds.
 
 - [minetest forum topic](https://forum.minetest.net/viewtopic.php?f=9&t=17155)
 - [imgur album](https://imgur.com/a/B408K)
+
+## installation
+
+Each folder is a separate Minetest mod.  Copy all of the folders to your Minetest mods folder, and activate one mod at a time.  Note that fractal_helpers is just a batch of helper functions which are used by the other mods for fractal generation.
+
+## usage
+
+1. Create a new world in Minetest.  Do not enter the world.
+2. With the world selected, click the "Configure" button.
+3. Enable the mod for the fractal object you want to generate.
+4. Click the "Play" button.
+
+## configuration
+
+You can configure how a fractal generates by editing the init.lua script associated with it.  Every fractal generation script has a Parameters section.  You can edit these parameters to change the size of the fractal, the blocks used in the fractal, or other properties depending on the fractal.

greek_cross_fractal/init.lua

@@ -15,7 +15,7 @@ The maximum fractal iteration you can use depends on the
 cross_size you use.  This chart shows the maximum
 iteration for several cross_size values.  You can
 calculate the fractal size for a given size and iteration
-using the formula on line 35.
+using the formula on line 38.
 
 | cross_size | fractal_iteration | fractal_size |
 |------------|-------------------|--------------|

octahedron_flake/init.lua

@@ -15,7 +15,7 @@ The maximum fractal iteration you can use depends on the
 octahedron_size you use.  This chart shows the maximum
 iteration for several octahedron_size values.  You can
 calculate the fractal size for a given size and iteration
-using the formula on line 36.
+using the formula on line 39.
 
 | octahedron_size | fractal_iteration | fractal_size |
 |-----------------|-------------------|--------------|