chore: Add MPL-2.0 LICENSE header to WearOS code
I will be initially licensing my contributions under the MPL-2.0 since I
consider it a fairer license than the GPL.
- See https://jhale.dev/posts/why-i-use-the-mpl/
Since the MPL is compatible with the GPL, this dual-licensing does not
create any licensing conflicts.
Any concerns about dual licensing can be sent to me privately. I am
happy to answer any questions and address any concerns.