🐳 : Further Docker build Cleanup & Docs Update (#1502)

* refactor: post-cleanup changes:
- add more unnecessary paths to .dockerignore
- remove librechat.yaml from main compose file (prevents from being required)
- do not create librechat.yaml during build (does nothing)

* docs: make config file instructions easier to read, more info throughout other docs

* docs: add custom config to menu

* Update custom_config.md

* Update docker_compose_install.md

docker-compose.override.yml.example

@@ -8,6 +8,11 @@ version: '3.4'
 # # SAVE THIS FILE AS 'docker-compose.override.yaml'
 # # AND USE THE 'docker-compose build' & 'docker-compose up -d' COMMANDS AS YOU WOULD NORMALLY DO
 
+# # USE LIBRECHAT CONFIG FILE
+#   api:
+#     volumes:
+#       - ./librechat.yaml:/app/librechat.yaml
+
 # # BUILD FROM LATEST IMAGE
 #   api:
 #     image: ghcr.io/danny-avila/librechat-dev:latest