update placeholder text

templates/base.html

@@ -68,7 +68,7 @@
 				</div class="nav-item dropdown">
 			</div clas="navbar-nav">
 			<form class="form-inline my-2 my-lg-0" method="POST" action="/search">
-				<input class="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search" name="term">
+				<input class="form-control mr-sm-2" type="search" placeholder="Search by title" aria-label="Search" name="term">
 				<button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
 			</form>
 		</div class="collapse navbar-collapse">