Fix bug and docs assuming progressBar min is 0 instead of getMin()

This code and docs predates the existence of get/setMin() on ProgressBar,
should have been updated when we introduced the new min property.

Test: Ran TalkBack
Bug: 74357845
Change-Id: I318f26bb8ecacc5ecdbf7d026d8568f871cf2369
(cherry picked from commit 25886a16)