Linear Algebra empty documentation chapter added

docs/CMakeLists.txt

@@ -96,6 +96,7 @@ add_custom_command(OUTPUT "${SPHINX_INDEX_FILE}"
                        "${CMAKE_CURRENT_SOURCE_DIR}/use_cases/custom_representation_types.rst"
                        "${CMAKE_CURRENT_SOURCE_DIR}/use_cases/extensions.rst"
                        "${CMAKE_CURRENT_SOURCE_DIR}/use_cases/legacy_interfaces.rst"
+                       "${CMAKE_CURRENT_SOURCE_DIR}/use_cases/linear_algebra.rst"
                        "${CMAKE_CURRENT_SOURCE_DIR}/use_cases/unknown_units_and_dimensions.rst"
                        "${CMAKE_CURRENT_SOURCE_DIR}/usage.rst"
                        "${DOXYGEN_INDEX_FILE}"

docs/use_cases.rst

@@ -13,4 +13,5 @@ Use Cases
     use_cases/unknown_units_and_dimensions
     use_cases/legacy_interfaces
     use_cases/custom_representation_types
+    use_cases/linear_algebra
     use_cases/extensions

docs/use_cases/linear_algebra.rst

@@ -0,0 +1,5 @@
+.. namespace:: units
+
+Linear Algebra of Quantities
+============================
+