[mobile-broadband-provider-info] dtd: fix a spelling error

[Lubomir Rintel <lkundrak src gnome org>]

commit 10ebbca6a11059a7308883d43ff3a8bd72c57d1a
Author: Graham Inggs <graham inggs+gitlab gmail com>
Date:   Tue Sep 28 19:11:44 2021 +0000

    dtd: fix a spelling error
    
    https://gitlab.gnome.org/GNOME/mobile-broadband-provider-info/-/merge_requests/42

 serviceproviders.2.dtd | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/serviceproviders.2.dtd b/serviceproviders.2.dtd
index cc03238..8f87ed8 100644
--- a/serviceproviders.2.dtd
+++ b/serviceproviders.2.dtd
@@ -39,7 +39,7 @@
 <!ELEMENT standard EMPTY>
 <!ATTLIST standard type (cvvm|otmp|proprietary) #REQUIRED>
 <!-- Whether the carrier supports OTMP or CVVM for Visual Voicemail
-     Some carriers impliment their own proprietary standard.
+     Some carriers implement their own proprietary standard.
 -->
 
 <!ELEMENT destination-number (#PCDATA)>