Typo: documentation is not plural

Documentation can not be plural in English.

Author: mbeijen

tmpl/navigation.tmpl

@@ -5,7 +5,7 @@ var self = this;
     <h3 class="applicationName"><a href="index.html"><?js= env.conf.templates.applicationName ?></a></h3>
 
     <div class="search">
-        <input id="search" type="text" class="form-control input-sm" placeholder="Search Documentations">
+        <input id="search" type="text" class="form-control input-sm" placeholder="Search Documentation">
     </div>
     <ul class="list">
     <?js