docs: add ProtocolProbe to community projects (#1736)

## Motivation and Context
Adds ProtocolProbe to the Other section, in alphabetical order (between
polygraph and PulseFeed MCP Drift Watch).

ProtocolProbe (https://protocolprobe.com) is a free, neutral site with
dated, sourced facts about every server in the official registry: the
listing, npm/PyPI and GitHub repository checks, version history, and a
record of what changed each day (https://protocolprobe.com/mcp/changes).
The same facts are an open CC BY 4.0 dataset with a Zenodo DOI (all
versions: 10.5281/zenodo.23386799; also on Hugging Face and Kaggle) and
a public read-only API (https://protocolprobe.com/docs/api). It also
publishes a self-test command that operators run on their own machine
against their own server. ProtocolProbe does not grade servers and never
calls tools on servers that are not its own.

I am the maintainer of ProtocolProbe. AI disclosure: this PR (the
one-line change and this description) was prepared with an AI assistant
(Claude) and submitted from my account after I approved it.

## How Has This Been Tested?
Documentation only. Checked that the link loads, that the entry follows
the list's one-line format and alphabetical order, and that the file's
line endings are unchanged.

## Breaking Changes
None.

## Types of changes
- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [x] Documentation update

## Checklist
- [x] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [x] My code follows the repository's style guidelines
- [ ] New and existing tests pass locally
- [ ] I have added appropriate error handling
- [x] I have added or updated documentation as needed

## Additional context
Related to #1715, where I shared the same dated pulls as input for
periodic re-validation.

Author: Sultan57git

docs/community-projects.md

@@ -39,6 +39,7 @@ Self-hostable servers that implement the MCP Registry API specification.
 - [OtherVibes/mcp-publish-action](https://github.com/OtherVibes/mcp-publish-action) - GitHub Action for publishing MCP servers to the official registry
 - [PlugVet](https://plugvet.com) - Free directory that grades MCP servers from the official MCP Registry, plus Claude Code skills and plugins, from A to F on eight automated hygiene checks (permissions, install and update, network, secrets, agent instructions, obfuscation, licence, maintainer activity), showing the evidence and check date for each entry. A hygiene screen, not a security guarantee.
 - [polygraph](https://polygraph.so) - Independent behavioral security grades (A–F) for MCP servers from an open, reproducible harness, published as an adoption-ranked index with per-server reports
+- [ProtocolProbe](https://protocolprobe.com) - Free, dated facts about every server in the official registry (listing, npm/PyPI and repository checks, version history, daily changes), with an open CC BY 4.0 dataset (Zenodo DOI 10.5281/zenodo.23386799), a public API and a self-test CLI for operators' own servers. Never grades servers or calls other people's servers' tools.
 - [PulseFeed MCP Drift Watch](https://pulsefeed.dev/mcp/drift) - Daily external diff of the whole registry population, recording what changed in a server *after* it was listed: package ownership transferred, install script added in a later version, repository removed, package unpublished, a removed name republished by someone else. Free JSON/RSS feed filterable to your own packages, a README badge, and webhook alerts; series runs from 2026-07-30 and each day's manifest is timestamped into Bitcoin.
 
 ## Adding Your Project