Send caching headers for static content

docker/conf/apache2/sites-available/000-default.conf

@@ -23,6 +23,11 @@
 	Header set X-Frame-Options SAMEORIGIN
 	Header set Strict-Transport-Security "max-age=2592000;"
 
+	# Set caching headers for /static/ content.
+	<Location /static/>
+		Header set Cache-Control "max-age=31536000"
+	</Location>
+
 	# Configure negotiation.
 	LanguagePriority en it fr de es pt ca
 	ForceLanguagePriority Prefer Fallback