Documentation of -O1 in user guide

Summary

Location of documentation issue: the GHC user's guide

https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/using-optimisation.html

-O1 Means: “Generate good-quality code without taking too long about it.”

The only information we get here is:

The easiest way to see what -O (etc.) “really mean” is to run with -v, then stand back in amazement.

I tried -O1 -v but it does not list the optimizations included in -O1.

Proposed improvements or changes

• Add link to this list: https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/flags.html#optimisation-levels

• Possibly sober this up:

The easiest way to see what -O (etc.) “really mean” is to run with -v, then stand back in amazement.