Add a description how to source the API Keys

[jukey]

It would be awesome to add a more concrete description how to source the api keys in order to avoid using the --token parameter.

My suggestion would be:

Create a file called ~/.scalyrand add the following into it:

export scalyr_readlog_token='XXX'
export scalyr_readconfig_token='YYY'
export scalyr_writeconfig_token='ZZZ'

Now source the variable to your current shell by entering:

source ~/.scalyr

Now the parameter --token is not necessary any longer.