Update Getting Started doc to use alpha07
Update Getting Started doc to use alpha07

Looks like the Getting Started doc is still suggesting to use the
alpha06 of MDC. Given that the alpha07 was released several weeks ago,
I'm updating the gradle implementation line to use the latest version of
MDC.

GIT_ORIGIN_REV_ID=d9b4c752f215ec2ac7f420fce6fcef6b96831c84

Resolves https://github.com/material-components/material-components-android/pull/392

PiperOrigin-RevId: 256418728

material-components/material-components-android