Updated copy for archive/reactivate offers

refs https://github.com/TryGhost/Team/issues/1148

ghost/admin/app/components/modals/archive-offer.hbs

@@ -7,7 +7,7 @@
 
     <div class="modal-body">
         <p>
-            Are you sure you want to archive "<strong>{{@data.offer.name}}</strong>" ?
+            By archiving <strong>{{@data.offer.name}}</strong>, new members will no longer be able to subscribe using this offer. All members that previously redeemed <strong>{{@data.offer.name}}</strong> will remain unchanged.
         </p>
     </div>
 

ghost/admin/app/components/modals/unarchive-offer.hbs

@@ -1,21 +1,20 @@
 
 <div class="modal-content" {{on-key "Enter" (perform this.archiveOfferTask)}}>
     <header class="modal-header">
-        <h1>Unarchive offer</h1>
+        <h1>Reactivate offer</h1>
     </header>
     <button type="button" class="close" title="Close" {{on "click" @close}}>{{svg-jar "close"}}<span class="hidden">Close</span></button>
 
     <div class="modal-body">
         <p>
-            Are you sure you want to unarchive "<strong>{{@data.offer.name}}</strong>" ?
+            Reactivating <strong>{{@data.offer.name}}</strong> will immediately allow new members to subscribe using this offer.
         </p>
     </div>
 
     <div class="modal-footer">
         <button type="button" class="gh-btn" {{on "click" @close}}><span>Cancel</span></button>
         <GhTaskButton
-            @buttonText="Unarchive"
-            @successText="Unarchived"
+            @buttonText="Reactivate"
             @task={{this.unarchiveOfferTask}}
             @class="gh-btn gh-btn-black gh-btn-icon"
         />

ghost/admin/app/templates/offer.hbs

@@ -219,7 +219,7 @@
                         class="gh-btn gh-btn-black gh-btn-icon"
                         {{on "click" this.openConfirmUnarchiveModal}}
                     >
-                        <span>Activate offer</span>
+                        <span>Reactivate offer</span>
                     </button>
                 {{/if}}
             </div>