Added Readme file

Describe how to execute the WrapC tool to generate the Eiffel code to wrap libgit2

Author: jvelilla

library/Readme.md

@@ -0,0 +1,43 @@
+# How to generate the code?
+
+## Requirements
+You need to have a binary version of WrapC tool and be able to execute it form the library folder.
+
+Before to regenerate the generated code, remove the folder `generated_wrapper`. If you are using geant, just run `geant clean` in other 
+case remove it manually.
+
+## Using WrapC with geant
+$LIB_PATH is the path to the library folder where you checkout the wrap_libgit2 library.
+
+### Wrap libgit2 library
+
+Go to the $LIB_PATH/library
+
+```
+    geant wrap_c  -- Wrap C libgit2 library and generate the code under the folder generated_wrapper
+```
+
+### Compile the C library
+ ```
+    geant compile -- Build the C library, in this case generate the eif_libgit2.lib
+  ```
+
+***
+ 
+## Using WrapC without geant
+  
+$LIB_PATH is the path to the library folder where you checkout the wrap_libgit2 library.
+At the moment the tool require --output-dir and --full-header to be full paths.
+  
+### Wrap plplot library  
+  ```
+    wrap_c --verbose --output-dir=$LIB_PATH/library/generated_wrapper --full-header=$LIB_PATH/library/C/include/git2.h config.xml
+  ```
+
+### Compile the C library
+```
+  cd generated_wrapper\c\src
+  finish_freezing -library
+```
+
+