Tweak accessibility tree experiment description
Tweak accessibility tree experiment description

Bug: chromium:887173
Change-Id: I002b910b3f80fb4d4274999f4920d9d8de815b2f
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2726780
Commit-Queue: Jecelyn Yeen <f9d8706cc517861f2adda0a78fda4fb3953b5665@chromium.org>
Reviewed-by: Mathias Bynens <17a2cbc4e33156874a9862b0f530521117e66a3d@chromium.org>
Reviewed-by: Alex Rudenko <d8d88e7d7e77f69e23d1d1432231196fb8e02a62@chromium.org>

ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend