fixup: dev guide.

doc/developer_guide.md

@@ -199,15 +199,15 @@ Unit-tests related to checking that `DataType` API, go in
 Check related to empty arrays to in `tests/unit/test_empty_arrays.cpp`.
 
 #### Selections
-Anything selection related goes in `tests/unit/test_string.cpp`.
+Anything selection related goes in `tests/unit/test_high_five_selection.cpp`.
 This includes things like `ElementSet` and `HyperSlab`.
 
 #### Strings
 Regular write-read cycles for strings are performed along with the other types,
 see above. This should cover compatibility of `std::string` with all
 containers. However, additional testing is required, e.g. character set,
 padding, fixed vs. variable length. These all go in
-`tests/unit/test_high_five_string.cpp`.
+`tests/unit/test_string.cpp`.
 
 #### Specific Tests For Optional Containers
 If containers, e.g. `Eigen::Matrix` require special checks those go in files