Update README.md

added additional information for those who do not know how to use cargo or rust

README.md

@@ -9,6 +9,28 @@ This repo is a short and sweet response to Austins most recent video 'The Scienc
 
 [`cargo`](https://github.com/rust-lang/cargo) to compile the program
 
+# Building
+
+`cargo build --release`
+
+# Features
+
+You can disable default features to switch to less performant code like so
+
+`cargo build --release --no-default-features`
+
+however this will require you provide a seed to seed the manual random implementation
+
+`cargo build --release --no-default-features -- 789124`
+
+to enable specific features just use the -F flag like so
+
+`cargo build --release --no-default-features -F auto_thread_count -- 789124`
+
+or
+
+`cargo build --release --no-default-features -F auto_thread_count,rust_random`
+
 # Timings
 
 ### 1 billion