Add instruction for getting system info in Crosh.

Refer to the instruction given by @drinkcat in
https://github.com/drinkcat/chroagh/issues/54#issuecomment-58771224
Add instruction for getting system info in Crosh.

This time in the contributing section of Readme.

Refer to the instruction given by @drinkcat in
https://github.com/drinkcat/chroagh/issues/54#issuecomment-58771224
Reword 4bae48457043ebc8f420611311cb91a3844ec324
Move instruction for encrypting existing chroots
Add notice for avoiding perserving ownership issue

See issue #903
Update tip in Readme

Tell the users right away that they can disbale the proxy setting using -P
option. In case some users get panic, so they do not read the descriptions
carefully, when their proxies do not work and want to
disable them but just cannot find out how.
Add the type a usb/sd should be formatted for -m
fix errors
fix errors
Merge pull request #1231 from tonyxue/enchance-doc

Enchance documentations