chore: simplify plugin readmes, changelogs and manifest descriptions

plugins/warpgate/README.md

@@ -0,0 +1,25 @@
+# Warpgate
+
+Connect through a Warpgate SSH bastion. Its browser approval shows as a sign-in dialog and your saved password is sent for you.
+
+## Features
+
+- Connect through a [Warpgate](https://github.com/warp-tech/warpgate) SSH bastion.
+- Warpgate's browser approval shows as a sign-in dialog.
+- Your saved password is sent to Warpgate for you.
+
+## Settings
+
+### Host
+
+- Warpgate Gateway: this host connects through Warpgate.
+
+## Development
+
+```bash
+npm run build      # build into dist/
+npm run test       # run this plugin's tests
+npm run typecheck  # type-check this plugin
+```
+
+See `packages/plugin-sdk/ARCHITECTURE.md` for the plugin contract.