Error response from daemon: "OP_CONNECT_HOST" is not settable

[starbaser]

Hi, I'm attempting to install the plugin into my existing 1password connect docker environment and the following occurs:

$ docker plugin install mrmarble/opsd:latest OP_CONNECT_HOST="http://localhost:8080" OP_VAULT_NAME="$OP_VAULT_NAME" OP_CONNECT_TOKEN="$OP_CONNECT_HOST"
Plugin "mrmarble/opsd:latest" is requesting the following privileges:
 - network: [host]
 - mount: [/var/run/docker.sock]
 - capabilities: [CAP_SYS_ADMIN]
Do you grant the above permissions? [y/N] y
latest: Pulling from mrmarble/opsd
Digest: sha256:3b9b6bc1a430f2d00bb9a748cd750b1adae08519cf39fd441eda5f48b7a54a02
9680978e8995: Complete 
Error response from daemon: "OP_CONNECT_HOST" is not settable

Looking at the docker plugin example config it seems the settable key is needed, and after adding it to the plugin config the plugin is able to installed as listed, as well as being able to set the values with docker plugin set.

[MrMarble]

Fixed in #4