Include paragraph about SE_MANAGER_PATH env in Selenium Manager doc

[bonigarcia]

Description

This PR include a paragraph about the SE_MANAGER_PATH environment variable in Selenium Manager doc (in the "Alternative architectures" subsection).

Motivation and Context

I believe this env is not documented elsewhere.

Types of changes

• Change to the site (I have double-checked the Netlify deployment, and my changes look good)
• Code example added (and I also added the example to all translated languages)
• Improved translation
• Added new translation (and I also added a notice to each document missing translation)

Checklist

• I have read the contributing document.
• I have used hugo to render the site/docs locally and I am sure it works.

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