'make doc' -> 'make docs'

Author: Matthew-Whitlock

doc/CMakeLists.txt

@@ -30,10 +30,10 @@ list(APPEND DOXYGEN_ALIASES "unimplemented=@qualifier UNIMPLEMENTED @brief @html
 
 add_subdirectory(html)
 
-doxygen_add_docs(doc
+doxygen_add_docs(docs
     markdown/Introduction.md fake_init.h ../include ../src
     ALL
     COMMENT "Generate Fenix documentation")
-message(STATUS "Run `make doc` to build documentation")
+message(STATUS "Run `make docs` to build documentation")
 
 install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/man DESTINATION ${CMAKE_INSTALL_PREFIX})