Adding some documentation extensions

[s3inlc]

Added:

• wget download string for agent download (closes docs: Remove wget part from the installation #1546)
• information how to completely clean and start an instance (closes docs: Guide how to clean hashtopolis Instance & Backup #1545)
• some notes and help considering backup/restore (closes docs: Guide how to clean hashtopolis Instance & Backup #1545)

[Copilot]

Pull Request Overview

This PR adds documentation enhancements to improve user experience with agent installation and instance management. It addresses three specific user requests by providing clearer installation instructions and operational guidance.

• Added wget command option for agent downloads as an alternative to curl
• Included comprehensive backup and restore considerations section
• Added complete clean/reset procedure for fresh instance setup

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
doc/installation_guidelines/basic_install.md	Added wget download option and improved formatting with extra line spacing
doc/installation_guidelines/advanced_install.md	Added extensive backup/restore guidance and clean instance setup instructions

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[ObsidianOracle]

Is fine for me