Update README.md

Author: MichaelGrupp

README.md

@@ -5,13 +5,13 @@ A simple, minimalistic but still powerful command line parser in less than 100 l
 The library is header-only and only depends on the C++11 STL. This is not intended as a replacement for big libraries (e.g. boost::filesystem), rather as an option for quick tests and small projects.
 
 ***Features***
-
-* *organize flags in groups*
-* *mark groups as required, optional or "any of"*
-* *add flags and their descriptions to the groups*
-* *check if all flags are valid*
+* *check if a flag exists*
 * *get single parameter from flags*
 * *get multiple parameters from flags*
+* *organize flags in groups and mark them as required, optional or "any of"*
+* *add flags to the groups, and optionally their alternative flag and their description*
+* *automatically check if all flags are valid*
+* *automatically print help/usage messages*
 
 ## Platforms
 You will need a C++ compiler that supports C++11 regex, e.g. Clang >3.6 or GCC >4.9.
@@ -23,24 +23,45 @@ Automatic [unit tests](https://github.com/MichaelGrupp/MiniCommander/blob/master
 ## Installation
 Just drop the header file [MiniCommander.hpp](https://github.com/MichaelGrupp/MiniCommander/blob/master/MiniCommander.hpp) in your project and include it in your program.
 
-## Supported Formats
-* single flags
-    * can be named arbitrarily, e.g. `-f` or long version `--flag`
-    * check existence of a single flag with `optionExists("--flag")`
-* UNIX style multiple single flags
-    * `-xyz` will be parsed like `-x -y -z`, `--xyz` won't
-    * activate this behaviour by setting the optional `unixFlags`parameter of the constructor to `true`
-* single parameters
-    * a parameter appears after its flag, e.g.: `--param 100` or `--param=100`
-    * the parameter string can be accessed with `getParameter("--param")`
-* multiple parameters
-    * multiple parameters appear after their flag, e.g. `--multi first second third`
-    * `getMultiParameters("--multi")` returns the string vector of multiple parameters 
-
-The `checkFlags()` function checks if all required flags were given by the user. If parameters were not given, the parameter string returned by `getParameter` (or vector by `getMultiParameters`) is empty.
+## Supported Formats for Arguments
+
+By default, flags can be name arbitrarily. Single parameters appear after a flag (here: `-d`). Multiple space-separated parameters are also possible (here after `-f`).
+```
+-x -y -z -d param -f param1 param2 param3
+-x -y -z -d=param -f=param1 param2 param3
+```
+By setting the optional `unixFlags`parameter of the class constructor to `true`, multiple options can be combined if they're defined in single dash format (`-*`):
+```
+-xyz -d param
+-xyzd=param
+-xyzd param
+```
+which behaves the same as `-x -y -z -d=param`.
+
+* check existence of a single flag `-x` with `optionExists("-x")`
+* a parameter string can be accessed with `getParameter("-d")` 
+* `getMultiParameters("-f")` returns the parameter string vector of a multiple parameter flag
+
+If parameters were not given, the parameter string returned by `getParameter` (or vector by `getMultiParameters`) is empty.
+
+## Grouping Options with Policies
+The `checkFlags()` function automatically checks if all required flags were given by the user. Furthermore, automatic help messages can be generated with `printHelpMessage`. 
+
+To use these features, the command line options must be first grouped by their check policy: 
+* ***required*** - all options of this group must be given
+* ***optional*** - giving these options is not mandatory
+* ***anyOf*** - at least one option of the group must be given
+
+Example of a required option group:
+```c++
+ OptionGroup requiredExample(Policy::required, "required options");
+ paths.addOption("-d", "first required argument");
+ paths.addOption("-f", "other required argument", "--flag");
+```
+Note that an **optional long alternative** `--flag` of the `-f` flag was added. This group can now be added to a *MiniCommander* instance via `addOptionGroup`.
 
 ## Example Usage
-This code example [test.cpp](https://github.com/MichaelGrupp/MiniCommander/blob/master/test/test.cpp) shows how to use the command line interface functions offered by MiniCommander:
+This code example [test.cpp](https://github.com/MichaelGrupp/MiniCommander/blob/master/test/test.cpp) shows how to use all of the command line interface functions offered by MiniCommander:
 
 ```c++
 #include <iostream>