Text-overflow for description added

Current when description of the repo
becomes too long then text would overflow
the div we are trying to pertain desc in
But with this change we are adding some
`webkit` specific multi line
text-overflow in `.tagline` class so that
now it would show ... when it will overflow

assets/css/main.css

@@ -145,7 +145,10 @@ div.container {
 }
 
 .content-item p.tagline {
-    font-weight: normal;
+    display: -webkit-box;
+    overflow: hidden;
+    -webkit-line-clamp: 6;
+    -webkit-box-orient: vertical;
     font-size: 13px;
     line-height: 20px;
 }