[gnumeric] Introspection fix.

[Morten Welinder <mortenw src gnome org>]

commit 481af9057024508fccc3b55a3eda48173eb1f4e5
Author: Morten Welinder <terra gnome org>
Date:   Tue Mar 6 08:53:27 2018 -0500

    Introspection fix.

 src/workbook-view.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/workbook-view.c b/src/workbook-view.c
index 518a710..01c289c 100644
--- a/src/workbook-view.c
+++ b/src/workbook-view.c
@@ -1308,7 +1308,7 @@ workbook_view_new_from_input (GsfInput *input,
 /**
  * workbook_view_new_from_uri:
  * @uri: URI for file
- * @optional_format: Optional GOFileOpener
+ * @optional_format: (allow-none): Optional GOFileOpener
  * @io_context: Optional context to display errors.
  * @optional_encoding: Optional encoding for GOFileOpener that understand it
  *