docs(README): format code blocks for SSH key generation instructions

README.md

@@ -7,14 +7,3 @@
 #### 应用相关
 
 参见 [flux/README.md](flux/README.md)
-
-```shell
-ssh-keygen -t ed25519 -C "flux" -f ./flux-git-auth -N ""
-
-ssh-keyscan github.com > ./known_hosts
-
-kubectl -n infra-gitops create secret generic flux-git-auth \
- --from-file=identity=./flux-git-auth \
- --from-file=identity.pub=./flux-git-auth.pub \
- --from-file=known_hosts=./known_hosts
-```