fix(install): use the raw README URL for the version being installed #46

Problem

The installation flow points users or agents to an incorrect README location. The README should be fetched from Havesomecode/kibana-mcp-server using the Git reference corresponding to the version being installed.

Expected behavior

For an installation from master, use this raw URL:

https://raw.githubusercontent.com/Havesomecode/kibana-mcp-server/refs/heads/master/README.md

For other versions, resolve the URL using the actual installation reference:

• Branch: https://raw.githubusercontent.com/Havesomecode/kibana-mcp-server/refs/heads/<branch>/README.md
• Tag: https://raw.githubusercontent.com/Havesomecode/kibana-mcp-server/refs/tags/<tag>/README.md
• Commit: https://raw.githubusercontent.com/Havesomecode/kibana-mcp-server/<commit-sha>/README.md

Do not always fetch master when installing a tag or another ref: the instructions must match the version being installed. Do not assume the package version has a corresponding Git tag; use the resolved installation ref.

Acceptance criteria

• Find and correct the README link used by installation instructions, skills, and generated handoff messages.
• An installation from master produces the exact URL above.
• A tagged or commit-pinned installation reads the README at that ref, rather than silently falling back to master.
• Verify that the resulting URL retrieves the expected README for the selected ref.
• If the ref or README cannot be resolved, report the problem explicitly instead of presenting instructions from another version as matching the installation.

The incorrect link was reported by a user; its exact current value and originating file still need to be located.