Add external plugin keep-the-why (#2776)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

plugins/external.json

@@ -584,6 +584,31 @@
       "sha": "8b644bebc7e1f929c01d80788293a37872f480f8"
     }
   },
+  {
+    "name": "keep-the-why",
+    "description": "Preserves or recovers the reasoning behind a codebase — architectural decisions, rejected alternatives, workarounds, incident learnings, operational constraints, and historical context the code itself cannot explain.",
+    "version": "0.5.2",
+    "author": {
+      "name": "Oliver Zehentleitner",
+      "url": "https://github.com/oliver-zehentleitner"
+    },
+    "repository": "https://github.com/oliver-zehentleitner/keep-the-why",
+    "homepage": "https://keepthewhy.com",
+    "license": "MIT",
+    "keywords": [
+      "documentation",
+      "context",
+      "decision-log",
+      "knowledge-management",
+      "onboarding",
+      "agents"
+    ],
+    "source": {
+      "source": "github",
+      "repo": "oliver-zehentleitner/keep-the-why",
+      "ref": "v0.5.2"
+    }
+  },
   {
     "name": "microsoft-docs",
     "description": "Access official Microsoft documentation, API references, and code samples for Azure, .NET, Windows, and more.",