doc: update plugin command documentation

Add use case for the --build-arg flag

README.md

@@ -254,6 +254,20 @@ This command will run the plugin container inside the AVS Docker network and rem
 
 The `--host` flag can be used to run the plugin container in the `host` network if the AVS Node Software is not running. To mount directories, files, and Docker volumes to the plugin container, use the `--volume` flag. All `plugin` command flags should be declared before the instance ID. To learn more about these options, run the `eigenlayer plugin --help` command.
 
+### Plugin build args
+
+If the plugin is built from a relative path inside the package or a remote context, the plugin image is built each time the plugin is executed. To pass build arguments to the plugin image build process, use the `--build-arg` flag, which is a map of key-value pairs. For example:
+
+```bash
+eigenlayer plugin \
+ --build-arg arg1=value1 \
+ --build-arg arg2=value2 \
+ mock-avs-default \
+ --port 8080
+```
+
+The `--build-arg` flag can be used multiple times to pass multiple build arguments. Should be declared before the instance ID to be recognized as a plugin build argument, and not as a plugin execution argument.
+
 ### Passing arguments to the plugin
 
 To pass arguments to the plugin container ENTRYPOINT, append them after the AVS instance ID, as follows:

cli/plugin.go

@@ -48,6 +48,23 @@ func PluginCmd(d daemon.Daemon) *cobra.Command {
 
   This will mount the /tmp directory of the host inside the plugin container at 
   /tmp, and the plugin-v volume at /data.
+
+- Using build arguments:
+
+  For the cases that the plugin is build from a relative path inside the package
+  or a remote context, the plugin image is built each time the plugin is executed.
+  To pass build arguments to the plugin image, use the "--build-arg" flag, which
+  is a map of key-value pairs. For example:
+
+    $ eigenlayer plugin \
+       	--build-arg arg1=value1 \
+       	--build-arg arg2=value2 \
+    	mock-avs-default \
+     	--port 8080
+
+  The "--build-arg" flag can be used multiple times to pass multiple build
+  arguments. Should be declared before the instance ID to be recognized as a
+  plugin build argument, and not as a plugin execution argument.
 `,
 
 		PreRunE: func(cmd *cobra.Command, args []string) error {