Update ruby error recovery test to reflect grammar tweaks

test/fixtures/error_corpus/readme.md

@@ -0,0 +1,8 @@
+The Error Corpus
+================
+
+This directory contains corpus tests that exercise error recovery in a variety of languages.
+
+These corpus tests provide a simple way of asserting that error recoveries are "reasonable" in a variety of situations. But they are also somewhat *overspecified*. It isn't critical that error recovery behaves *exactly* as these tests specify, just that most of the syntax tree is preserved despite the error.
+
+Sometimes these tests can start failing when changes are pushed to the parser repositories like `tree-sitter-ruby`, `tree-sitter-javascript`, etc. Usually, we just need to tweak the expected syntax tree.

test/fixtures/error_corpus/ruby_errors.txt

@@ -14,6 +14,6 @@ c
     method: (identifier)
     (ERROR (heredoc_beginning))
     arguments: (argument_list
-      (heredoc_body (heredoc_end))
+      (heredoc_body (heredoc_content) (heredoc_end))
       (identifier)
       (MISSING ")"))))