Fix breadcrumbs layout on mobile

Author: alexchorman

_theme/breadcrumb.html

@@ -1,6 +1,6 @@
 <div class="breadcrumbs-section" role="navigation" aria-label="related navigation">
 	<div class="content-container">
-		<div class="d-flex justify-content-between">
+		<div class="d-flex justify-content-between flex-wrap">
 			<ol class="breadcrumb">
 				<li class="breadcrumb-item">
 					<a href="{{ pathto(master_doc) }}">{{ shorttitle|e }}</a>