Update README: Fix broken anchor link

[bartwr]

Just a typo fix.

[CLAassistant]

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:white_check_mark: schnuerle
:x: bartwr
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[schnuerle]

Thank you for catching this!

Please sign the SLA and I will merge to dev:

https://cla-assistant.io/openmobilityfoundation/mobility-data-specification?pullRequest=755

[schnuerle]

Hi @bartwr you need to please sign the SLA for us to accept this change:

https://cla-assistant.io/openmobilityfoundation/mobility-data-specification?pullRequest=755

[schnuerle]

I will update this as part of the #816 work.

[schnuerle]

Fixed with PR #824