docs: clarify imports_granularity behavior with comments

Author: calebcartwright

CHANGELOG.md

@@ -8,6 +8,7 @@
 
 ### Fixed
 
+- Don't change granularity of imports containing comments with `imports_granularity` if doing so could lose or misplace those comments [#5311](https://github.com/rust-lang/rustfmt/pull/5311)
 - Prevent rustfmt from removing trailing comments at the end of files annotated with inner `#![rustfmt::skip]` attributes [#5033](https://github.com/rust-lang/rustfmt/issues/5033)
 - Fixed various `error[internal]: left behind trailing whitespace"` issues:
   - Remove trailing whitespace when formatting a where clause who's bounds have an empty right hand side [#5012](https://github.com/rust-lang/rustfmt/issues/5012) [#4850](https://github.com/rust-lang/rustfmt/issues/4850)

Configurations.md

@@ -1705,6 +1705,8 @@ How imports should be grouped into `use` statements. Imports will be merged or s
 - **Possible values**: `Preserve`, `Crate`, `Module`, `Item`, `One`
 - **Stable**: No (tracking issue: [#4991](https://github.com/rust-lang/rustfmt/issues/4991))
 
+Note that rustfmt will not modify the granularity of imports containing comments if doing so could potentially lose or misplace said comments.
+
 #### `Preserve` (default):
 
 Do not change the granularity of any imports and preserve the original structure written by the developer.