docs: improve documentation of remove_nested_blocks

Configurations.md

@@ -2235,32 +2235,34 @@ Works similarly to [`remove_nested_parens`](#remove_nested_parens), but removes
 - **Possible values**: `true`, `false`
 - **Stable**: No
 
+Blocks with any sort of comments or attributes, `unsafe` and `const` blocks will not be removed.
 
-#### `true`:
+#### `false` (default):
 ```rust
 fn main() {
     {
-        foo();
+        {
+            // comment
+            {
+                foo();
+            }
+        }
     }
 }
 ```
 
-#### `false` (default):
+#### `true`:
 ```rust
 fn main() {
     {
+        // comment
         {
-            {
-                {
-                    foo();
-                }
-            }
+            foo();
         }
     }
 }
 ```
 
-
 ## `reorder_impl_items`
 
 Reorder impl items. `type` and `const` are put first, then macros and methods.

src/expr.rs

@@ -676,12 +676,15 @@ fn rewrite_block_inner(
     context: &RewriteContext<'_>,
     shape: Shape,
     can_be_removed: bool,
+    // ^ this is a fix for const blocks, which are not removed, but are passed identically to blocks
 ) -> RewriteResult {
     debug!("rewrite_block : {:?}", context.snippet(block.span));
     let prefix = block_prefix(context, block, shape)?;
 
     let no_attrs = attrs.is_none() || attrs.unwrap().is_empty();
 
+    // If the option `remove_nested_blocks` is enabled, we remove all unnecessary nested blocks.
+    // Blocks with any sort of comments or attributes, unsafe and const blocks will not be removed.
     if context.config.remove_nested_blocks()
         && can_be_removed
         && prefix.is_empty()