touch_updater: Improve doc comment for `find_fw_link_path`

It wasn't completely clear what the function did with each argument, so
I added an example.

BUG=None
TEST=None

Change-Id: I8539d7ca41bb872cfe4d42da414573ebb3e4f07b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/touch_updater/+/1955832
Tested-by: Harry Cutts <hcutts@chromium.org>
Auto-Submit: Harry Cutts <hcutts@chromium.org>
Reviewed-by: Sean O'Brien <seobrien@chromium.org>
Commit-Queue: Harry Cutts <hcutts@chromium.org>
1 file changed