Add Pipelines documentation

[grasmash]

This should outline:

• Intended Pipelines workflow
• Initialization instructions
• Links to external resources

[geerlingguy]

Following; I just integrated with BLT/GitHub, and have some notes.

[grasmash]

#828 merged.

[geerlingguy]

One note so far—it might be helpful to add a command to move the pipelines executable into a location that's in the default $PATH, like mv pipelines /usr/local/bin or something along those lines. Or just a note that you should place it in a place that's accessible in your $PATH.

Otherwise, people might end up committing the pipelines executable to their project repo :)