Highlight Rust doc comments with markdown

The test changes are needed because of the changes to comment parsing.
The `1..36` to `1..37` change is because line comments now consume the
newline.

helix-core/src/syntax.rs

@@ -2687,10 +2687,10 @@ mod test {
             )
         };
 
-        test("quantified_nodes", 1..36);
+        test("quantified_nodes", 1..37);
         // NOTE: Enable after implementing proper node group capturing
-        // test("quantified_nodes_grouped", 1..36);
-        // test("multiple_nodes_grouped", 1..36);
+        // test("quantified_nodes_grouped", 1..37);
+        // test("multiple_nodes_grouped", 1..37);
     }
 
     #[test]
@@ -2861,7 +2861,7 @@ mod test {
 
     #[test]
     fn test_pretty_print() {
-        let source = r#"/// Hello"#;
+        let source = r#"// Hello"#;
         assert_pretty_print("rust", source, "(line_comment)", 0, source.len());
 
         // A large tree should be indented with fields:

languages.toml

@@ -234,7 +234,7 @@ args = { attachCommands = [ "platform select remote-gdb-server", "platform conne
 
 [[grammar]]
 name = "rust"
-source = { git = "https://github.com/tree-sitter/tree-sitter-rust", rev = "0431a2c60828731f27491ee9fdefe25e250ce9c9" }
+source = { git = "https://github.com/tree-sitter/tree-sitter-rust", rev = "35f4a5b8a29c161402e89dba83dcdc9876ba1dac" }
 
 [[language]]
 name = "sway"

runtime/queries/rust/highlights.scm

@@ -51,7 +51,7 @@
 (lifetime
   "'" @label
   (identifier) @label)
-(loop_label
+(label
   "'" @label
   (identifier) @label)
 

runtime/queries/rust/injections.scm

@@ -1,6 +1,10 @@
-([(line_comment) (block_comment)] @injection.content
+([(line_comment !doc) (block_comment !doc)] @injection.content
  (#set! injection.language "comment"))
 
+((doc_comment) @injection.content
+ (#set! injection.language "markdown")
+ (#set! injection.combined))
+
 ((macro_invocation
    macro:
      [