journal: make "end comment" optional, like ledger

The "comment" directive longer requires an "end comment", and will
extend to the end of the file(s) without it.

doc/manual.md

@@ -530,9 +530,8 @@ Lines in the journal beginning with a semicolon (`;`) or hash (`#`) or
 asterisk (`*`) are comments, and will be ignored. (Asterisk comments
 make it easy to treat your journal like an org-mode outline in emacs.)
 
-Also, anything between
-[`comment` and `end comment` directives](#multi-line-comments) is a
-(multi-line) comment.
+Also, anything between [`comment` and `end comment` directives](#multi-line-comments) is a (multi-line) comment.
+If there is no `end comment`, the comment extends to the end of the file.
 
 You can attach comments to a transaction by writing them after the
 description and/or indented on the following lines (before the

hledger-lib/Hledger/Read/JournalReader.hs

@@ -995,7 +995,7 @@ multilinecommentp = do
   string "comment" >> many spacenonewline >> newline
   go
   where
-    go = try (string "end comment" >> newline >> return ())
+    go = try (eof <|> (string "end comment" >> newline >> return ()))
          <|> (anyLine >> go)
     anyLine = anyChar `manyTill` newline