cookbooks/devel: updated the version for devel tutorials

docs/cookbooks/devel/core.md

@@ -1,6 +1,6 @@
 # Core Cookbook
 
-Version: Kamailio SIP Server v5.8.x (devel)
+Version: Kamailio SIP Server v6.1.x (devel)
 
 ## Overview
 

docs/cookbooks/devel/pseudovariables.md

@@ -1,6 +1,6 @@
 # Pseudo-Variables
 
-Version: Kamailio SIP Server v6.0.x (devel)
+Version: Kamailio SIP Server v6.1.x (devel)
 
 ## Introduction
 

docs/cookbooks/devel/selects.md

@@ -1,6 +1,6 @@
 # Selects Variables
 
-Version: Kamailio SIP Server v6.0.x (devel)
+Version: Kamailio SIP Server v6.1.x (devel)
 
 The **select** is a READ-ONLY "function", that helps to get direct
 access to some parts of SIP message within the script (like @to,

docs/cookbooks/devel/transformations.md

@@ -1,6 +1,6 @@
 # Transformations
 
-Version: Kamailio SIP Server v5.8.x (devel)
+Version: Kamailio SIP Server v6.1.x (devel)
 
     Main author:
        Daniel-Constantin Mierla <miconda (at) gmail.com>