[UPD] : update README.md

Author: aiekick

README.md

@@ -72,9 +72,10 @@ included in the Lib_Only branch for your convenience.
 - Directory bookmarks
 - Directory manual entry (right click on any path element)
 - Optional 'Confirm to Overwrite" dialog if file exists
+- C Api (succesfully tested with CimGui)
 - Thumbnails Display (agnostic way for compatibility with any backend, sucessfully tested with OpenGl and Vulkan)
 - The dialog can be embedded in another user frame than the standard or modal dialog
-- C Api (succesfully tested with CimGui)
+- Can tune validation buttons (placements, widths, inversion) 
 
 ## Singleton Pattern vs. Multiple Instances
 
@@ -577,6 +578,40 @@ with [ImGuiFontStudio](https://github.com/aiekick/ImGuiFontStudio), which I wrot
 
 ImGuiFontStudio uses ImGuiFileDialog! Check it out.
 
+## Tune the validations button group
+
+You can specify :
+- the width of "ok" and "cancel" buttons, by the set the defines "okButtonWidth" and "cancelButtonWidth"
+- the alignement of the button group (left, right, middle, etc..) by set the define "okCancelButtonAlignement"
+- if you want to have the ok button on the left and cancel button on the right or inverted by set the define "invertOkAndCancelButtons"
+
+just see theses defines in the config file
+```cpp
+//Validation buttons
+//#define okButtonString " OK"
+//#define okButtonWidth 0.0f
+//#define cancelButtonString " Cancel"
+//#define cancelButtonWidth 0.0f
+//alignement [0:1], 0.0 is left, 0.5 middle, 1.0 right, and other ratios
+//#define okCancelButtonAlignement 0.0f
+//#define invertOkAndCancelButtons false
+```
+with Alignement 0.0 => left
+
+![alignement_0.0.gif](https://github.com/aiekick/ImGuiFileDialog/blob/master/doc/alignement_0.0.png)
+
+with Alignement 1.0 => right
+
+![alignement_1.0.gif](https://github.com/aiekick/ImGuiFileDialog/blob/master/doc/alignement_1.0.png)
+
+with Alignement 0.5 => middle
+
+![alignement_0.5.gif](https://github.com/aiekick/ImGuiFileDialog/blob/master/doc/alignement_0.5.png)
+
+ok and cancel buttons inverted (cancel on the left and ok on the right)
+
+![validation_buttons_inverted.gif](https://github.com/aiekick/ImGuiFileDialog/blob/master/doc/validation_buttons_inverted.png)
+
 ## Embedded in other frames :
 
 The dialog can be embedded in another user frame than the standard or modal dialog