secodn measurement: reorganize and unify data format

experimental_setup/sandbox/Friction_measurment/2/README.md

experimental_setup/sandbox/Friction_measurment/README.md

...imental_setup/sandbox/Friction_measurment/friction1_1.dat

...imental_setup/sandbox/Friction_measurment/friction1_2.dat

...imental_setup/sandbox/Friction_measurment/friction1_3.dat

...imental_setup/sandbox/Friction_measurment/friction1_4.dat

...imental_setup/sandbox/Friction_measurment/friction1_5.dat

...imental_setup/sandbox/Friction_measurment/friction2_1.dat

...imental_setup/sandbox/Friction_measurment/friction2_2.dat

...imental_setup/sandbox/Friction_measurment/friction2_3.dat

...imental_setup/sandbox/Friction_measurment/friction2_4.dat

...imental_setup/sandbox/Friction_measurment/friction2_5.dat