can't include Scope.run in a Doc

[stew]

Input:

```unison
> {{ {Scope.run} }}

Output:

I found a value of type: (Unit ->{g1, Scope s1} r) ->{g1} r where I expected to find: (Unit ->{g, Scope s} 𝕩) -> 𝕣

  2 | > {{ {Scope.run} }}

[pchiusano]

Dupe of #3499