Fix up spacing in stdlib/contracts
```
"#m
= fun l => %blame% l,
+
blameWith
| doc m#"
Raise blame with respect to a given label and a custom error message.
```
"#m
= fun msg l => %blame% (%tag% msg l),
+
fromPred
| doc m#"
Generate a contract from a boolean predicate.
```
"#m
= fun pred l v => if pred v then v else %blame% l,
+
tag
| doc m#"
Attach a tag, or a custom error message, to a label. If a tag was
