docs: cache-bust Glama score badge and simplify alt text

[aliasunder]

Summary

• The Glama score badge in the README renders blank on GitHub because GitHub's Camo proxy cached the SVG while Glama's score was still pending (badge added in docs: add Glama listing badge to README #57). The markdown itself was already correct — this is a stale-image-cache issue, not a code bug.
• Appending ?v=2 to the score.svg URL gives GitHub a new image URL, forcing a fresh Camo fetch of the now-computed grade.
• Also simplified the alt text vault-cortex MCP server → vault-cortex to match the renamed server on Glama.

Test plan

• After merge, view the README on github.com (hard-refresh) and confirm the Glama badge shows the computed grade instead of a blank/placeholder badge.
• If it still shows stale art, bump ?v=2 → ?v=3 to force another Camo miss.

https://claude.ai/code/session_01KnvnMoDuU6QkYrCna54CqT

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Generated by Claude Code

Summary by CodeRabbit

• Documentation
  • Updated the MCP server Glama badge reference in README to use the latest version with improved caching parameters.