wrong powershell instructions for setting env variables

[DanielJump]

On this page:
https://github.com/sourcegraph/src-cli#installation

It says:
$env.SRC_ENDPOINT = 'https://sourcegraph.example.com'
$env.SRC_ACCESS_TOKEN = 'my-token'

It should be:
$env:SRC_ENDPOINT = 'https://sourcegraph.example.com'
$env:SRC_ACCESS_TOKEN = 'my-token'

[mrnugget]

Thanks for reporting. Fix is here: #1025