feat(core): add installation command to the documentation

[loicmathieu]

This will add the following section on top of the plugin documentation page (unless it's the core plugin):

Installation

If you use one of our Docker images tagged *-full this plugin is already included.
If not, you can install it with the following command:

./kestra plugins install io.kestra.plugin:plugin-script-shell:LATEST

This command will automatically install the latest available version. You can replace LATEST with a specific version or a version range like [0.12,0.13.0-SNAPSHOT).

[sonarcloud]

Quality Gate passed

Kudos, no new issues were introduced!

0 New issues
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[anna-geller]

Suggested change

	## Installation
	If you use one of our Docker images tagged __*-full__, this plugin is already included.
	If not, you can install it with the following command:
	```shell
	./kestra plugins install io.kestra.plugin:{{ name }}:LATEST
	```
	This command will automatically install the latest available version. You can replace `LATEST` with a specific version or a version range like `[0.12,0.13.0-SNAPSHOT)`.
	::alert{type="info"}
	If you use a [base Docker image](https://kestra.io/docs/installation/docker#official-docker-images) without plugins, you can install the plugin using the following command:
	```shell
	./kestra plugins install io.kestra.plugin:{{ name }}:LATEST

You can replace LATEST with a specific version or a version range e.g. [0.14,0.15.0-SNAPSHOT).
::

[anna-geller]

This looks like a great addition. As discussed, it would be awesome to include it as a short info box right before the Properties.

The decision to include it is motivated by customers' requests who found this command really useful + it's a helpful reminder to install a plugin if not available yet.

[anna-geller]

closing for now in favor of #3174