split How-To in 2 parts, include PR comments/critique

Author: Ron Hildebrandt

docs/index.md

@@ -29,6 +29,7 @@ A series of tutorials giving you an overview on how to store or convert your dat
 
 How-to guides provide step-by-step instructions for a wide range of tasks:
 
+
 - [Build your own pynxtools plugin](how-tos/build-a-plugin.md)
 - [Using pynxtools test framework](how-tos/using-pynxtools-test-framework.md)
 - [Creation of NeXus files by Python](how-tos/create-nexus-files-by-python.md)