Added Rotation mention in the ReadMe

README.md

@@ -216,7 +216,7 @@ c3d.parameter("GroupName", param); // Add the parameter to the c3d structure
 Please note that if this parameter already exist in the group named "GroupName", then this parameter is replaced by the new one. Otherwise, if it doesn't exist or the group doesn't exist, then it is added to the group or the group is created then the parameter is added. For more information on how to set a new parameter from `c3d` accessors methods, please refer to the documentation on [c3d](https://pyomeca.github.io/Documentation/ezc3d/classezc3d_1_1c3d.html).
 
 #### Get data
-Point and analogous data are the core of the C3D file. To understand the structure though it is essential to understand that everything is based on points. For example, the base frame rate the point frame rate, while the analogous data is based on the number of data per point frame. Therefore to get a particular point in time, you must get the data at a certain frame and specify which point you are interested in, while to get a particular analogous data you must also specify the subframe.
+Point and analogous data are the core of the C3D file (please note that rotation data are also available, but are non-standard). To understand the structure though it is essential to understand that everything is based on points. For example, the base frame rate the point frame rate, while the analogous data is based on the number of data per point frame. Therefore to get a particular point in time, you must get the data at a certain frame and specify which point you are interested in, while to get a particular analogous data you must also specify the subframe.
 ```C++
 ezc3d::c3d c3d("path_to_c3d.c3d");
 ezc3d::DataNS::Points3dNS::Point pt(new_c3d.c3d.data().frame(f).points().point(0));