README.md: Add other examples and output sample

README.md

@@ -4,14 +4,40 @@ Docker image verifying the code format with clang-format
 
 ## Getting Started
 
-Mount the source folder in the `src` working directory and run the format checker
+The following command will mount the current working directory folder to the `src` working directory, and check its format
 
 `docker run --rm -v $(pwd):/src witekio/clang-format-checker`
 
 The return code will be
-* `1` if any formatting errors are found, and printed in the standard output.
+* `non-zero` if any formatting errors are found, and printed in the standard output.
 * `0` if no issue was found
 
+```
+$ docker run -v $(pwd):/src --rm witekio/clang-format-checker                                      2 ↵
+--- ./testCode/File.cpp	(original)
++++ ./testCode/File.cpp	(reformatted)
+@@ -3,18 +3,13 @@
+ 
+ #include "MyHeader.h"
+ 
+-MyClass::MyClass() 
++MyClass::MyClass()
+-    : arg(new Other(std::string("string"), 4))
+-  : arg(new Other(std::string("string"), 4))
+```
+
+## Changing the style
+
+The style used by `clang-format` can be defined by providing a `.clang-format` file in your source folder. For more information, see [clang-format style options](https://clang.llvm.org/docs/ClangFormatStyleOptions.html)
+
+## Specify the files to check
+
+Check recursively .h/.cpp files excluding `vendors` folder
+
+`docker run --rm -v $(pwd):/src witekio/clang-format-checker "--extensions=h,cpp --exclude vendors"`
+
+For more information, you can check [`run-clang-format`](https://github.com/Sarcasm/run-clang-format) repository
+
 ## License
 
 This project is licensed under the MIT License - see the [LICENSE.md](LICENSE.md) file for details