docs: address CodeRabbit review feedback (3 findings)

- README.md: wrap the Windows MSIX Claude Desktop config in PRE-PYPI
  markers so pre-PyPI readers get the --from git+... form alongside the
  post-PyPI survivor (mirrors the lines 157-188 pattern).
- docs/launch/show-hn.md: add a concrete "Demo query" line to both the
  pre-PyPI feedback draft and the post-PyPI Show HN draft, using
  asyncio.TaskGroup on Python 3.13 as the example.
- docs/launch/reddit-posts.md: add an r/ClaudeAI launch variant
  alongside r/Python and r/LocalLLaMA, leaning on the Claude Desktop /
  Claude Code MCP integration angle as the audience-specific hook.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: ayhammouda

README.md

@@ -439,6 +439,25 @@ uv cache clean python-docs-mcp-server
 The MSIX-packaged version of Claude Desktop on Windows may have restricted PATH
 access. If `uvx` is not found, specify the full path in your config:
 
+<!-- PRE-PYPI: remove the GitHub-source config and the "After PyPI publishing, use:" lead-in after the first PyPI publish; the post-PyPI config fence below survives -->
+```json
+{
+  "mcpServers": {
+    "python-docs": {
+      "command": "C:\\Users\\YOU\\.local\\bin\\uvx.exe",
+      "args": [
+        "--from",
+        "git+https://github.com/ayhammouda/python-docs-mcp-server.git",
+        "python-docs-mcp-server"
+      ]
+    }
+  }
+}
+```
+
+After PyPI publishing, use:
+<!-- /PRE-PYPI -->
+
 ```json
 {
   "mcpServers": {