Update README.md

Removed scan2text and added mass can --readscan info.
Update masscan.8

Removed scan2text info, added --readscan in its place.
Update masscan.8.markdown

Removed scan2test refrences and added --readscan info
Update masscan.8.markdown

Format update
warnings
Merge branch 'master' of https://github.com/robertdavidgraham/masscan
Merge pull request #30 from dmaynor/master

removed scan2text from docs