Add custom SSL for Lab configuration page

[AlexIchenskiy]

Description

This PR adds a page on adding custom SSL certificates to Memgraph Lab, along with new environment variables to the Install and connect page.

Pull request type

Please check what kind of PR this is:

• Fix or improvement of an existing page
• New documentation page, release related

Related PRs and issues

PR this doc page is related to:
memgraph/lab#913

Checklist:

• Make sure all relevant tech details are documented
  • Update reference pages (e.g. clauses, functions, flags, experimental, monitoring)
  • Search for the feature you are working on (mentions) and make updates if needed
  • Provide a basic example of usage
  • In case your feature is an Enterprise one, list it under ME page and mark its page with Enterprise (example).
• Check all content with Grammarly
• Perform a self-review of my code
• The build passes locally
• My changes generate no new warnings or errors
• Add a corresponding label
• If release-related, add a product and version label
• If release-related, add release note on product PR

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Name	Status	Preview	Comments	Updated (UTC)
documentation	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Nov 5, 2024 0:43am

[katarinasupe]

All looks great. I just pushed minor changes. General comment: we don't use title case for section titles.

Since this is related to the release, I rebased it.