all.bash: update usage
all.bash: update usage

The all.bash usage information is updated to include descriptions
for go mod tidy and go tests.

Change-Id: I1c4fdeaa72c41a4e41d48020d0b46ba037462aec
Reviewed-on: https://go-review.googlesource.com/c/vulndb/+/359411
Trust: Julie Qiu <8d32267b6b4884cf35adeaccde2b6857ae11aace@golang.org>
Reviewed-by: Jonathan Amsterdam <e3d3698b2ccd5955e4adf250d0785062d0f9018b@google.com>

golang/vuln,golang/vuln