[PATCH] Correct doxygen framing for libnotmuch.h

[Daniel Kahn Gillmor]

Apparently doxygen needs its comments formatted in a specific way to
notice that the group is closed.

Without this fix, with doxygen 1.8.16-2 we see:

```
doxygen ./doc/doxygen.cfg
…/notmuch/lib/notmuch.h:2322: warning: end of file while inside a group
```

Signed-off-by: Daniel Kahn Gillmor <dkg at fifthhorseman.net>
---
 lib/notmuch.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/notmuch.h b/lib/notmuch.h
index 34666b88..ceb5a018 100644
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -2312,7 +2312,7 @@ notmuch_indexopts_destroy (notmuch_indexopts_t *options);
  */
 notmuch_bool_t
 notmuch_built_with (const char *name);
-/* @} */
+/**@}*/
 
 #pragma GCC visibility pop
 
-- 
2.25.1