HSTS preload + X-XSS enables

**HSTS Preloading:**
In its strongest and recommended form, the [HSTS policy](https://www.chromium.org/hsts) includes all subdomains, and indicates a willingness to be “preloaded” into browsers:
`Strict-Transport-Security: max-age=31536000; includeSubDomains; preload`

**X-Xss-Protection:**
`1; mode=block` which tells the browser to block the response if it detects an attack rather than sanitising the script.

roles/matrix-nginx-proxy/templates/nginx/conf.d/matrix-bot-go-neb.conf.j2

@@ -3,7 +3,8 @@
 {% macro render_vhost_directives() %}
 	gzip on;
 	gzip_types text/plain application/json application/javascript text/css image/x-icon font/ttf image/gif;
-	add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
+	add_header Strict-Transport-Security "max-age=31536000; includeSubDomains; preload" always;
+	add_header X-XSS-Protection "1; mode=block";;
 	add_header X-Content-Type-Options nosniff;
 {% for configuration_block in matrix_nginx_proxy_proxy_bot_go_neb_additional_server_configuration_blocks %}
 	{{- configuration_block }}

roles/matrix-nginx-proxy/templates/nginx/conf.d/matrix-dimension.conf.j2

@@ -3,7 +3,8 @@
 {% macro render_vhost_directives() %}
 	gzip on;
 	gzip_types text/plain application/json application/javascript text/css image/x-icon font/ttf image/gif;
-	add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
+	add_header Strict-Transport-Security "max-age=31536000; includeSubDomains; preload" always;
+	add_header X-XSS-Protection "1; mode=block";
 	add_header X-Content-Type-Options nosniff;
 {% for configuration_block in matrix_nginx_proxy_proxy_dimension_additional_server_configuration_blocks %}
 	{{- configuration_block }}

roles/matrix-nginx-proxy/templates/nginx/conf.d/matrix-jitsi.conf.j2

@@ -3,7 +3,8 @@
 {% macro render_vhost_directives() %}
 	gzip on;
 	gzip_types text/plain application/json application/javascript text/css image/x-icon font/ttf image/gif;
-	add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
+	add_header Strict-Transport-Security "max-age=31536000; includeSubDomains; preload" always;
+	add_header X-XSS-Protection "1; mode=block";
 	add_header X-Content-Type-Options nosniff;
 {% for configuration_block in matrix_nginx_proxy_proxy_jitsi_additional_server_configuration_blocks %}
 	{{- configuration_block }}

roles/matrix-nginx-proxy/templates/nginx/conf.d/matrix-sygnal.conf.j2

@@ -3,7 +3,8 @@
 {% macro render_vhost_directives() %}
 	gzip on;
 	gzip_types text/plain application/json application/javascript text/css image/x-icon font/ttf image/gif;
-	add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
+	add_header Strict-Transport-Security "max-age=31536000; includeSubDomains; preload" always;
+	add_header X-XSS-Protection "1; mode=block";
 	add_header X-Content-Type-Options nosniff;
 	add_header X-Frame-Options DENY;
 {% for configuration_block in matrix_nginx_proxy_proxy_sygnal_additional_server_configuration_blocks %}