Minor fix to CONTRIBUTING.md.
Minor fix to CONTRIBUTING.md.

Test: N/A
Change-Id: Ic13a25ce983895d9d3746fc5340c4d2ced3ec31c

androidx/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,androidx/androidx,androidx/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,AndroidX/androidx,AndroidX/androidx,AndroidX/androidx,AndroidX/androidx,androidx/androidx,androidx/androidx,androidx/androidx,AndroidX/androidx,AndroidX/androidx,AndroidX/androidx,AndroidX/androidx