docs: noted --coverage aliased by --collectCoverage (#6741)
docs: noted --coverage aliased by --collectCoverage (#6741)

## Summary

Noting that `--coverage` maps to `--collectCoverage` in docs since the latter is not listed anywhere.

## Test plan

None necessary.

facebook/jest,ide/jest,facebook/jest,ide/jest,bookman25/jest,bookman25/jest,facebook/jest,cpojer/jest,ide/jest,cpojer/jest,bookman25/jest,cpojer/jest