Replace Kernel Search configuration section with link to /docs/bots

The Kernel Search configuration steps were wrong to expose. Kernel's
own Web Bot Auth identities (Kernel Agent, Kernel Search) are already
approved by Cloudflare, Vercel, Akamai, etc. Replace the build/env-var
instructions with a short note pointing to /docs/bots and telling
readers to contact support if they want to sign with Kernel's identities.

Author: ulziibay-kernel

browsers/bot-detection/web-bot-auth.mdx

@@ -149,38 +149,13 @@ kernel extensions build-web-bot-auth \
   --upload my-web-bot-auth
 ```
 
-### 4. Kernel Search configuration
+### 4. Using Kernel's bot identities
 
-Kernel Search uses a distinct Web Bot Auth identity from Kernel's user-driven
-agent traffic:
-
-- User-Agent: `KernelSearchBot`
-- Signature-Agent: `https://search.bot.kernel.sh`
-- Key directory:
-  `https://search.bot.kernel.sh/.well-known/http-message-signatures-directory`
-
-To build a browser extension for Kernel Search, use the Kernel Search Ed25519
-private key (JWK) and upload it under a distinct extension name:
-
-```bash
-kernel extensions build-web-bot-auth \
-  --to ./web-bot-auth-search-ext \
-  --key ./kernel-search.jwk \
-  --signature-agent https://search.bot.kernel.sh \
-  --upload web-bot-auth-search
-```
-
-For host-proxy based signing, configure the Search crawler's host-proxy
-environment with:
-
-```bash
-HOST_PROXY_WEB_BOT_AUTH_ENABLED=true
-HOST_PROXY_WEB_BOT_AUTH_KEY_PATH=/path/to/kernel-search-private-key.pem
-HOST_PROXY_WEB_BOT_AUTH_DIRECTORY_URL=https://search.bot.kernel.sh
-```
-
-The signing key must correspond to the public key hosted by
-`search.bot.kernel.sh`.
+Kernel's own Web Bot Auth identities are already approved by Cloudflare, Vercel,
+Akamai, and other bot-verification providers. If you want to sign requests with
+one of Kernel's identities rather than your own, [contact Kernel support](https://www.kernel.sh/docs/info/support).
+See [Bots and agents](/docs/bots) for the list of identities and their key
+directories.
 
 ### 5. Register with Vercel and other Web Bot Auth-aware directories (optional)