adding README.md for main executable

Author: davidson16807

demo/8-interaction/README.md

@@ -0,0 +1,21 @@
+# Basic Usage
+
+## Ubuntu
+
+```bash
+./test.out 11 120000
+```
+
+## Windows
+
+```bash
+./test.exe 11 120000
+```
+
+The first two arguments are seed parameters. Minor changes to these parameters will result in a new terrain layout at the start of simulation. Running the simulation twice with same parameters will produce the same terrain layout.
+
+For best results, we recommend keeping seed parameters at the same orders of magnitude shown above. 
+
+If arguments are not specified, a set of default seed parameters will be used. This will run a simulation starting from a default world that's used to test how changes to code affect simulation behavior.
+
+On Windows, you can simply click the executable. This will run a simulation starting from the default world.

demo/8-interaction/_test.cpp

@@ -113,10 +113,11 @@ namespace minerals{
 
 int main(int argc, char *argv[]) {
   std::vector<std::string> arguments(argv, argv + argc); 
-  std::cout << std::to_string(argc) << std::endl;
   float seed1(argc<=1? 12.0f : std::stoi(arguments[1]));
   float seed2(argc<=2? 1.1e4f : std::stoi(arguments[2]));
 
+  std::cout << "seed parameters: " << std::to_string(seed1) << ", " << std::to_string(seed2) << std::endl;
+
   // initialize GLFW
   if (!glfwInit()) {
     std::cout << stderr << " ERROR: could not start GLFW3" << std::endl;