fix typo

src/doc/tutorials/data_model_tutorial.rst

@@ -76,8 +76,8 @@ properties, so you can search for all experiments where the properties
 match your desired criteria, for example those with cell lines which
 were described in publications of a certain author.
 
-What if need to change my data model?
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+What if I need to change my data model?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Science moves fast, and your infrastructure should be able to follow
 just as swiftly. The data model in LinkAhead was designed to be