Fix matadata collection configuration formatting

Author: xFrednet

clippy_lints/src/utils/internal_lints/metadata_collector.rs

@@ -344,11 +344,15 @@ fn parse_config_field_doc(doc_comment: &str) -> Option<(Vec<String>, String)> {
         if let Some(split_pos) = doc_comment.find('.');
         then {
             let mut doc_comment = doc_comment.to_string();
-            let documentation = doc_comment.split_off(split_pos);
+            let mut documentation = doc_comment.split_off(split_pos);
 
             doc_comment.make_ascii_lowercase();
             let lints: Vec<String> = doc_comment.split_off(DOC_START.len()).split(", ").map(str::to_string).collect();
 
+            // Format documentation correctly
+            // split off leading `.` from lint name list and indent for correct formatting
+            documentation = documentation.trim_start_matches('.').trim().replace("\n ", "\n    ");
+
             Some((lints, documentation))
         } else {
             None
@@ -781,8 +785,6 @@ impl<'a, 'hir> intravisit::Visitor<'hir> for ApplicabilityResolver<'a, 'hir> {
             }
         };
 
-        // TODO xFrednet 2021-03-01: support function arguments?
-
         intravisit::walk_expr(self, expr);
     }
 }