Document convenience methods on Edge: apply, pipe and run

[ptomecek]

The documentation should make users aware of the following convenience methods on Edge: apply, pipe and run, with some simple examples of how they can be leveraged to simplify the syntax or work with csp more easily.

apply: https://github.com/Point72/csp/blob/main/csp/impl/wiring/edge.py#L136
pipe: https://github.com/Point72/csp/blob/main/csp/impl/wiring/edge.py#L157
run: https://github.com/Point72/csp/blob/main/csp/impl/wiring/edge.py#L173

[ptomecek]

Added a new section on Edge methods to https://github.com/Point72/csp/wiki/1.-Generic-Nodes-(csp.baselib)
Happy to move it if needed. The other most suitable place for it seemed to be the Introduction.