README updates

[jason0x43]

Some quick updates for the README...

• "like jQuery" -> "similar to jQuery"
• "Once finished, the test will look like..." -> make sure it's clear a file needs to be edited
• Update link(s) to Leadfoot docs
• Describe briefly (or link to discussion about) how WebDriver cloud service tunnels work
• Local selenium example?

[magdiel01]

https://theintern.io/leadfoot/Command.html doesn't work

[jason0x43]

Wow, apparently the updates weren't that quick.