Add "Who's using Redis".

app.rb

@@ -160,6 +160,7 @@ def gravatar_hash(email)
   end
 
   on get, path("topics"), segment do |_, _, name|
+    @css = [:topics, name]
     @body, @title = topic("#{documentation_path}/topics/#{name}.md")
     @related_commands = related_commands_for(name)
 

views/documentation.md

@@ -37,6 +37,8 @@ low level.
 * [Internals](/topics/internals): learn details about how Redis is
 implemented under the hood.
 
+* [Who's using it?](/topics/whos-using-redis)
+
 Tutorials
 ---
 

views/layout.haml

@@ -11,7 +11,7 @@
     %title
       = [@title, "Redis"].compact.join(" – ")
 
-  %body
+  %body(class="#{@css.join(" ") if @css}")
     %header
       .container
         %a(href="/")

views/topics.sass

@@ -52,3 +52,21 @@ article
         &:first-child
           font-size: 22px
           line-height: 22px
+
+body.topics
+  &.whos-using-redis
+    ul:first-of-type
+      text-align: center
+      list-style-type: none
+      margin: 15px
+
+      li
+        margin: 10px 10px
+        padding: 0
+        display: inline-block
+        vertical-align: middle
+
+        img
+          vertical-align: middle
+          max-width: 200px
+          max-height: 76px