docs(bots): add bot message send example

Signed-off-by: Michael Bell <mb@igloos.one>

docs/bots.md

@@ -330,6 +330,54 @@ Bots can also send message. On the sending process the same signature/verificati
         + `413 Payload Too Large` When the message was longer than the allowed limit of 32000 characters (or 1000 until Nextcloud 16.0.1, check the `spreed => config => chat => max-length` capability for the limit)
         + `429 Too Many Requests` When `401 Unauthenticated` was triggered too often
 
+#### Sample bash script:
+
+```bash
+#!/bin/bash
+
+# Required environment variables:
+#   NC_URL: The URL of the Nextcloud instance (e.g., "https://nextcloud.example.com")
+#   TOKEN: The token of the conversation
+#   SECRET: Shared secret that is specified when installing a bot
+#   MESSAGE: The message to be sent
+
+# Check if required variables are set
+if [ -z "$NC_URL" ]; then
+    echo "Error: NC_URL is not set."
+    exit 1
+fi
+
+if [ -z "$TOKEN" ]; then
+    echo "Error: TOKEN is not set."
+    exit 1
+fi
+
+if [ -z "$SECRET" ]; then
+    echo "Error: SECRET is not set."
+    exit 1
+fi
+
+if [ -z "$MESSAGE" ]; then
+    echo "Error: MESSAGE is not set."
+    exit 1
+fi
+
+# Generate a random header and signature
+RANDOM_HEADER=$(openssl rand -hex 32)
+MESSAGE_TO_SIGN="${RANDOM_HEADER}${MESSAGE}"
+SIGNATURE=$(echo -n "${MESSAGE_TO_SIGN}" | openssl dgst -sha256 -hmac "${SECRET}" | cut -d' ' -f2)
+
+# Send the message
+curl -X POST "${NC_URL}/ocs/v2.php/apps/spreed/api/v1/bot/${TOKEN}/message" \
+  -H "Content-Type: application/json" \
+  -H "Accept: application/json" \
+  -H "OCS-APIRequest: true" \
+  -H "X-Nextcloud-Talk-Bot-Random: ${RANDOM_HEADER}" \
+  -H "X-Nextcloud-Talk-Bot-Signature: ${SIGNATURE}" \
+  -d '{"message":"'"${MESSAGE}"'"}'
+```
+
+
 ## Reacting to a chat message
 
 Bots can also react to a message. The same signature/verification method is applied.