feat(cli): add --var shorthand for --variable (#8710)

`--variable` is used frequently enough to deserve a shorthand. Unfortunately,
`-v` is taken by verbose, and `-V` is too easily confused with version or
verbose, so we're left with "--var".

examples/templates/envbox/README.md

@@ -35,10 +35,10 @@ Coder. Consult the [migration](https://coder.com/docs/v2/latest/templates/parame
 documentation for details on how to do so.
 
 To supply values to existing existing Terraform variables you can specify the
-`--variable` flag. For example
+`-V` flag. For example
 
 ```bash
-coder templates create envbox --variable namespace="mynamespace" --variable max_cpus=2 --variable min_cpus=1 --variable max_memory=4 --variable min_memory=1
+coder templates create envbox --var namespace="mynamespace" --var max_cpus=2 --var min_cpus=1 --var max_memory=4 --var min_memory=1
 ```
 
 ## Contributions

examples/templates/fly-docker-image/README.md

@@ -22,8 +22,8 @@ This template provisions a [code-server](https://github.com/coder/code-server) i
 
 ```bash
 coder templates create fly-docker-image \
-  --variable fly_api_token=$(flyctl auth token) \
-  --variable fly_org=personal
+  --var fly_api_token=$(flyctl auth token) \
+  --var fly_org=personal
 ```
 
 > If the Coder server is also running as a fly.io app, then instead of setting variable `fly_api_token` you can also set a fly.io secret with the name `FLY_API_TOKEN`