misc: remove outdated example doc

Makefile

@@ -164,7 +164,6 @@ docker-nydusify-image-test: docker-static
 		-v $(current_dir):/nydus-rs $(dind_cache_mount) nydusify-smoke TestDockerHubImage
 
 # Run integration smoke test in docker-in-docker container. It requires some special settings,
-# refer to `misc/example/README.md` for details.
 docker-smoke: docker-nydus-smoke docker-nydusify-smoke
 
 contrib-build: nydusify ctr-remote nydus-overlayfs
@@ -223,14 +222,3 @@ nydus-overlayfs-clean:
 docker-static:
 	docker build -t nydus-rs-static --build-arg RUST_TARGET=${RUST_TARGET_STATIC} misc/musl-static
 	docker run --rm ${CARGO_BUILD_GEARS} -e RUST_TARGET=${RUST_TARGET_STATIC} --workdir /nydus-rs -v ${current_dir}:/nydus-rs nydus-rs-static
-
-docker-example: all-static-release
-	cp ${current_dir}/target/${RUST_TARGET_STATIC}/release/nydusd misc/example
-	cp ${current_dir}/target/${RUST_TARGET_STATIC}/release/nydus-image misc/example
-	cp contrib/nydusify/cmd/nydusify misc/example
-	docker build -t nydus-rs-example misc/example
-	@cid=$(shell docker run --rm -t -d --privileged $(dind_cache_mount) nydus-rs-example)
-	@docker exec $$cid /run.sh
-	@EXIT_CODE=$$?
-	@docker rm -f $$cid
-	@exit $$EXIT_CODE

docs/containerd-env-setup.md

@@ -34,7 +34,7 @@ $ sudo tee /etc/nydus/nydusd-config.fusedev.json > /dev/null << EOF
         "timeout": 5,
         "connect_timeout": 5,
         "retry_limit": 4,
-        "auth": "YOUR_LOGIN_AUTH="
+        "auth": ""
       }
     },
     "cache": {
@@ -61,7 +61,7 @@ Please refer to the nydusd [doc](./nydusd.md) to learn more options.
 ⚠️ Note:
 
 - The `device.backend.config.scheme` is the URL scheme for the registry. Leave it empty for automatic detection, or specify `https` or `http` depending on your registry server configuration.
-- The `device.backend.config.auth` is the base64 encoded `username:password` required by nydusd to lazily pull image data from an authenticated registry. The nydus snapshotter will automatically read the authentication information from the `$HOME/.docker/config.json` configuration file. If you are using a registry that requires authentication, you should replace `YOUR_LOGIN_AUTH=` with your own login information.
+- The `device.backend.config.auth` is the base64 encoded `username:password` authentication string required by nydusd to lazily pull image data from an authenticated registry. The nydus snapshotter will automatically read it from the `$HOME/.docker/config.json` configuration file, or you can also fill it with your own.
 - The `device.backend.config.skip_verify` allows you to skip the insecure https certificate checks for the registry, only set it to `true` when necessary. Note that enabling this option is a security risk for the connection to registry, so you should only use this when you are sure it is safe.
 - The `fs_prefetch.enable` option enables nydusd to prefetch image data in background, which can make container startup faster when it needs to read a large amount of image data. Set this to `false` if you don't need this functionality when it brings disk and network pressure.