Readme or Not

What's new

1. add Scoop checkver alias to bin/checkver.ps1
2. add persist_link similar to persist, make unportable file out of $ScoopDir under persist control
3. add install.ps1/Set-Value method to update config value
4. support bucket sorting:
   1. scoop bucket add <name> [<repo>] [<priority>]
   2. scoop bucket alter <name> <priority>
5. support Github Proxy, config key is gh_proxy

What's wrong

1. for now persist_link only support one of user or global mode, many software only support current user mode, and others only support global mode. so just forget global mode