Update description for debug.renderengine.backend

Bug: N/A
Test: N/A
Flag: EXEMPT comment-only change
Change-Id: Ia192c9c5d3562a5e51b4f17433b6b2f337ae8ebb
Merged-In: Ib9b8abb25f4894f1b50b6286720c2abf89ca74e2
1 file changed