Adds load on startup instructions to README.md

[danieluhl]

Adds an optional setup step that others may find useful for restoring the previous session state when the program loads

[nicksp]

Looking good and works as expected.

[V4G4X]

Which session to restore is determined by the name of the sessions right?

Suppose I have the following sessions:

.Wezterm Session layout
├── Session A
│   ├── Edit Tab
│   ├── Build Tab
│   `── Deploy Tab
`── Session B
    ├── Zshrc config
    `── Wezterm config

If we automate load on startup like this, how will it know whether to populate Session B's state? or Session A's state?

We need something to spin up multiple workspaces (assuming every workspace can be spun up).