Use US english (license) in all places

Change-Id: I5fa99627a1c3302dd905d78149e5f32c7315a5c7

documentation/addons/addons-cval.asciidoc

 ---
-title: Installing Commercial Vaadin Add-on Licence
+title: Installing Commercial Vaadin Add-on License
 order: 5
 layout: page
 ---
 
 [[addons.cval]]
-= Installing Commercial Vaadin Add-on Licence
+= Installing Commercial Vaadin Add-on License
 
 The commercial Vaadin add-ons require installing a license key before using
 them. The license keys are development licenses and checked during widget set

documentation/addons/addons-maven.asciidoc

 +
 image::img/directory-activate.png[width=50%, scaledwidth=70%]
 +
-For official Vaadin add-ons, see <<addons-cval#addons.cval, "Installing Commercial Vaadin Add-on Licence">> for more information.
+For official Vaadin add-ons, see <<addons-cval#addons.cval, "Installing Commercial Vaadin Add-on License">> for more information.
 
 . _In Vaadin 7.6 and older_: You need to compile the widget set as described in <<addons.maven.compiling>>.
 

documentation/addons/addons-overview.asciidoc

 projects for free, and many have a trial period for closed-source development.
 Commercial Vaadin add-ons distributed under the CVAL license require installing
 a license key as instructed in
-<<dummy/../../../framework/addons/addons-cval#addons.cval, "Installing Commercial Vaadin Add-on Licence">>.
+<<dummy/../../../framework/addons/addons-cval#addons.cval, "Installing Commercial Vaadin Add-on License">>.
 
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