Create passwd.md

Added a few exemples, and basic description of passwd
Update passwd.md

Added info about the {{options}} flag, as requested.
Clarify OS support
add ss.md
Move pgrep to common instead of only OS X
Adds missing quote to say command
Merge pull request #124 from jeroenj/patch-1

Adds missing quote to say command
Merge pull request #123 from Tenzer/pgrep-move-to-common

Move pgrep to common instead of only OS X
Merge pull request #122 from notpeter/master

Fixes #121 Added man
Merge pull request #101 from 007N/patch-2

Create passwd.md
ss: refine examples
passwd: cleanup style to be similar to other pages
Merge pull request #119 from felixonmars/ss

add ss.md
Merge pull request #109 from ZDroid/os-support

Clarify OS support
Updated ZFS commands