add units in Points to make it readable by mokka

[Ipuch]

I built a c3d with the previous guidelines but got a problem when opened it because the unit was missing.
So I added a line to provide help to users.

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This change is 

[pariterre]

Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @Ipuch)

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README.md line 511 at r1 (raw file):

# Fill it with random data
c3d['parameters']['POINT']['UNITS']['value'] = ['m']

Vicon uses "mm" as default, should we?

[Ipuch]

Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @pariterre)

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README.md line 511 at r1 (raw file):

Previously, pariterre (Pariterre) wrote…

Vicon uses "mm" as default, should we?

This was more consistent with the random values after that bounded within 0 and 1.

[pariterre]

Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @Ipuch)