Update readme.md

readme.md

@@ -3,9 +3,10 @@ A small D library to generate the google authenticator code.
 
 inspired from https://github.com/tilaklodha/google-authenticator 
 
-- Install D Language https://dlang.org/ 
+- Install a D Language compiler https://dlang.org/ 
 - Install Dub package manager 
  - On OSX run `brew install dub`.
+ - On Ubuntu `snap install --classic dub`
  - Follow instructions on https://code.dlang.org/ for other OSes.
 
 
@@ -24,5 +25,25 @@ The library exposes two functions:
 
 more details on the algorithm on https://en.wikipedia.org/wiki/HMAC-based_One-time_Password_algorithm
 
+usage:
+1. add the library as a dependency in your dub project:
+
+```
+$ dub add gauthenticator
+```
+2. use the library by calling getTOTPToken() or getHOTPToken() functions
+
+```
+import std.stdio;
+import gauthenticator;
+
+void main()
+{
+ writeln(getTOTPToken("foobarbaz"));
+}
+``` 
+
+
+