small fixes to the documentation

docs/index.rst

@@ -4,7 +4,7 @@
    contain the root `toctree` directive.
 
 pyrost
-=====
+======
 
 Python Robust Speckle Tracking (**pyrost**) is a library for wavefront
 metrology and sample imaging based on ptychographic speckle tracking

docs/reference/ab_fit_ref.rst

 pyrost Abberations Fitting
-=========================
+==========================
 
 .. automodule:: pyrost.abberations_fit
 

docs/reference/cxi_ref.rst

 pyrost CXI Protocol
-==================
+===================
 
 .. automodule:: pyrost.protocol
 

docs/reference/rst_c_ref.rst

 pyrost Core Functions
-====================
+=====================
 
 Core functions of the rst data processing 
 pipeline. All the functions are written in `Cython`_.

docs/reference/rst_dp_ref.rst

 pyrost Core Classes
-==================
+===================
 
 .. automodule:: pyrost.data_processing