fix: too_long_first_doc_paragraph suggests wrongly when first line too long (#14276)

Fixes #14274

changelog: [`too_long_first_doc_paragraph`]: fix wrong suggestion when
first line too long

clippy_lints/src/doc/too_long_first_doc_paragraph.rs

@@ -51,7 +51,11 @@ pub(super) fn check(
                 // We make this suggestion only if the first doc line ends with a punctuation
                 // because it might just need to add an empty line with `///`.
                 should_suggest_empty_doc = doc.ends_with('.') || doc.ends_with('!') || doc.ends_with('?');
+            } else if spans.len() == 2 {
+                // We make this suggestion only if the second doc line is not empty.
+                should_suggest_empty_doc &= !doc.is_empty();
             }
+
             let len = doc.chars().count();
             if len >= first_paragraph_len {
                 break;