Update README and examples

Author: pfultz2

README.md

@@ -1,4 +1,130 @@
 Args
 ====
 
-Simple and typesafe commandline parsing for C++14.
+Simple and typesafe commandline parsing for C++14. 
+
+Quickstart
+----------
+
+Simply provide a class with fields that is to be filled by command-line arguments:
+
+```cpp
+struct hello
+{
+    int count;
+    std::string name;
+
+    hello() : count(1)
+    {}
+
+    template<class F>
+    void parse(F f)
+    {
+        f(count, "--count", "-C", args::help("Number of greetings."));
+        f(name, "--name", "-N", args::help("The person to greet."), args::required());
+    }
+
+    void run()
+    {
+        for(int i=0;i<count;i++) printf("%s\n", name.c_str());
+    }
+};
+
+int main(int argc, char const *argv[]) {
+    args::parse<hello>(argc, argv);
+}
+```
+
+The command then could be run like this:
+
+```
+$ hello --name Paul --count 3
+Paul
+Paul
+Paul
+
+```
+
+The args library will auto-generate help info:
+
+```
+$ hello --help
+Usage: hello [options...]
+
+  Simple program that greets NAME for a total of COUNT times.  
+
+Options: 
+
+            -h, --help Show help  
+ --count, -C [integer] Number of greetings.  
+   --name, -N [string] The person to greet.
+```
+
+In addition, nested commands can be created:
+
+```cpp
+struct cli : args::group<cli>
+{};
+
+struct initdb : cli::command<initdb>
+{
+    initdb() {}
+    static const char* help()
+    {
+        return "Initialize database";
+    }
+    void run()
+    {
+        printf("Initialize database\n");
+    }
+};
+
+struct dropdb : cli::command<dropdb>
+{
+    dropdb() {}
+    static const char* help()
+    {
+        return "Delete database";
+    }
+    void run()
+    {
+        printf("Delete database\n");
+    }
+};
+
+int main(int argc, char const *argv[]) {
+    args::parse<cli>(argc, argv);
+}
+
+```
+
+So each subcommand can be ran like this:
+
+```
+$ cli initdb
+Initialize database
+```
+
+```
+$ cli dropdb
+Delete database
+```
+
+In addition help is generated for subcommands as well:
+
+```
+$ cli --help
+Usage: cli [options...] [command]
+
+  Command-line interface to manage a database  
+
+Options: 
+
+ -h, --help Show help  
+
+Commands: 
+
+     dropdb Delete database  
+     initdb Initialize database  
+
+```

examples/basic.cpp

@@ -2,6 +2,10 @@
 
 struct hello
 {
+    static const char* help()
+    {
+        return "Simple program that greets NAME for a total of COUNT times.";
+    }
     int count;
     std::string name;
 
@@ -21,7 +25,8 @@ struct hello
     }
 };
 
-int main(int argc, char const *argv[]) {
+int main(int argc, char const *argv[]) 
+{
     args::parse<hello>(argc, argv);
 }
 

examples/groups.cpp

@@ -1,7 +1,12 @@
 #include <args.hpp>
 
 struct cli : args::group<cli>
-{};
+{
+    static const char* help()
+    {
+        return "Command-line interface to manage a database";
+    }
+};
 
 struct initdb : cli::command<initdb>
 {
@@ -29,7 +34,8 @@ struct dropdb : cli::command<dropdb>
     }
 };
 
-int main(int argc, char const *argv[]) {
+int main(int argc, char const *argv[]) 
+{
     args::parse<cli>(argc, argv);
 }