[gtkmm-documentation] Fix typo in my recent ColumnRecord commit

[Daniel Boles <dboles src gnome org>]

commit a0fb80ab4a36eb82c929226cfa2dcc0b711db51a
Author: Daniel Boles <dboles src gmail com>
Date:   Mon Jan 15 14:35:04 2018 +0000

    Fix typo in my recent ColumnRecord commit
    
    Thanks to Kjell for pointing this out.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=792482#c10

 docs/tutorial/C/index-in.docbook |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/docs/tutorial/C/index-in.docbook b/docs/tutorial/C/index-in.docbook
index 1230f9d..ce62a8a 100644
--- a/docs/tutorial/C/index-in.docbook
+++ b/docs/tutorial/C/index-in.docbook
@@ -2386,7 +2386,7 @@ As a <classname>TreeModelColumnRecord</classname> describes structure, not data,
 it can be shared among multiple models, and this is preferable for efficiency.
 However, the instance (such as <varname>m_Columns</varname> here) should usually
 not be static, because it often needs to be instantiated after
-<application>glibmm</application> has been ininitialized. The best solution is
+<application>glibmm</application> has been initialized. The best solution is
 to make it a lazily instantiated singleton, so that it will be constructed
 on-demand, whenever the first model accesses it.
 </para>