Add build/ to export-ignore and gitignore, mount family-nav-graph in Docker

.gitattributes

@@ -1,4 +1,5 @@
 # Exclude dev files from distribution ZIP
+build/                 export-ignore
 node_modules/          export-ignore
 docker/                export-ignore
 resources/js/modules/  export-ignore

.gitignore

@@ -1,5 +1,6 @@
 node_modules/
 .build/
+build/
 vendor/
 dist/
 *.log

docker/docker-compose.yml

@@ -17,6 +17,7 @@ services:
       - webtrees_data:/var/www/webtrees/data
       - ..:/var/www/webtrees/modules_v4/full-diagram
       - /home/alex/.local/src/webtrees_bocken_theme/BockenTheme:/var/www/webtrees/modules_v4/BockenTheme
+      - /home/alex/.local/src/webtrees_family_navigator_graph:/var/www/webtrees/modules_v4/family-nav-graph
     depends_on:
       db:
         condition: service_healthy