update README

README.md

@@ -1,14 +1,16 @@
 # MEXlibCZI
 
-a [MEX-file](https://www.mathworks.com/help/matlab/call-mex-file-functions.html) for reading [CZI-documents](https://www.zeiss.com/microscopy/int/products/microscope-software/zen/czi.html)
+a [MEX-file](https://www.mathworks.com/help/matlab/call-mex-file-functions.html) for reading and writing [CZI-documents](https://www.zeiss.com/microscopy/int/products/microscope-software/zen/czi.html)
 
 # Description
 
 This project provides a [MEX File Function](https://www.mathworks.com/help/matlab/call-mex-file-functions.html) which allows to
-directly open and read a [CZI-documents](https://www.zeiss.com/microscopy/int/products/microscope-software/zen/czi.html).  
+directly read and write [CZI-documents](https://www.zeiss.com/microscopy/int/products/microscope-software/zen/czi.html).  
 It is based on [libCZI](https://github.com/ptahmose/libCZI).
 ![MEXlibCZI](./doc/pictures/intro.PNG "MEXlibCZI")
 
+The available commands are documented here: [commands](./doc/commands.markdown)
+
 # Installing
 
 Binaries for Windows-x64 and Linux-x64 are provided on the [release-page](https://github.com/ptahmose/MEXlibCZI/releases) here on GitHub.