Update IS_vibrations_measurements.cfg

[Fragmon]

Include the acceleration value explicitly. Otherwise, it defaults to the max_acceleration value from the printer configuration, which in most cases does not match the printing acceleration. If people use the slicer limiter and set a high max_acceleration in the printer.cfg, it can potentially cause damage.

[Frix-x]

Oh you cut the grass under my foot haha
I wanted to work on something like that for some time to avoid running at max accel for the vib measurement since this usually give wrong results that are not really interesting. I'll see how to base my work on this PR :)