Minor Updates

[jeremydaily]

Changed speed units to km/h. Fixed small spelling errors. Added clarity to vehicle network sources when using J1587 based data.

[BenGardiner]

Summary of changes, as-sent in an email to the group:

This changeset from Dr. Jeremy Daily fixes some of our typograhic mistakes as well as:

• proposing using km/h rather than m/s for speeds -- to match SAE J1939
• mapping several of the vehicle fault fields to specific J1939 SPNs
• using example floating point values for fields that should allow floating point
• defining top gear value as including transmission and axle ratios

The changes will be merged Monday May 6th unless there are changes in review.

I have not updated https://previewotapi.docs.apiary.io/ for these changes; please use the 'files changed' tab of the review request.

[BenGardiner]

thanks again, @jeremydaily . I merged these changes, preserving attribution, into a larger set of changes to resolve some conflicts: see pull request #128