User Guide contains confusing information about `-rtsopts` modes.

Currently the user guide section on `-rtsopts` specifies that -rtsopts=some is the default setting in the text under it, while the specified default is all.

"[this is the default setting] Enable only the “safe” RTS options: (Currently only -? and --info.) Any other RTS options on the command line or in the GHCRTS environment variable causes the program with to abort with an error message."

Happy to submit a patch if someone can confirm that all is actually the default, and that I'm not misunderstanding the meaning here.