read only update

src/students/Week_1_4/WS_1_4_Nonlinear_Rain.html

src/students/Week_1_4/WS_1_4_Nonlinear_Rain.zip

src/students/Week_1_4/WS_1_4_solution.html

src/teachers/Week_1_4/README.html

src/teachers/Week_1_4/WS_1_4_Nonlinear_Rain.html

src/teachers/Week_1_4/WS_1_4_Nonlinear_Rain.zip

src/teachers/Week_1_4/WS_1_4_solution.html