🐳 : 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

Dockerfile

@@ -6,10 +6,10 @@ WORKDIR /app
 
 # Allow mounting of these files, which have no default
 # values.
-RUN touch .env librechat.yaml
+RUN touch .env
 # Install call deps - Install curl for health check
 RUN apk --no-cache add curl && \
-    npm ci 
+    npm ci
 
 # React client build
 ENV NODE_OPTIONS="--max-old-space-size=2048"