Rollup merge of #104504 - compiler-errors:fru-syntax-note, r=estebank

Add a detailed note for missing comma typo w/ FRU syntax

Thanks to `@pierwill` for working on this with me!

Fixes #104373, perhaps `@alice-i-cecile` can comment on the new error for the example provided on that issue -- feedback is welcome.

```
error[E0063]: missing field `defaulted` in initializer of `Outer`
  --> $DIR/multi-line-fru-suggestion.rs:14:5
   |
LL |     Outer {
   |     ^^^^^ missing `defaulted`
   |
note: this expression may have been misinterpreted as a `..` range expression
  --> $DIR/multi-line-fru-suggestion.rs:16:16
   |
LL |           inner: Inner {
   |  ________________^
LL | |             a: 1,
LL | |             b: 2,
LL | |         }
   | |_________^ this expression does not end in a comma...
LL |           ..Default::default()
   |           ^^^^^^^^^^^^^^^^^^^^ ... so this is interpreted as a `..` range expression, instead of functional record update syntax
help: to set the remaining fields from `Default::default()`, separate the last named field with a comma
   |
LL |         },
   |          +

error: aborting due to previous error

For more information about this error, try `rustc --explain E0063`.
```

0 files changed, 0 insertions, 0 deletions