feat(client): Add support for monitoring gRPC endpoints (#1376)

* add grpc

* add gRPC to readme

README.md

@@ -121,6 +121,7 @@ Have any feedback or questions? [Create a discussion](https://github.com/TwiN/ga
   - [Monitoring a UDP endpoint](#monitoring-a-udp-endpoint)
   - [Monitoring a SCTP endpoint](#monitoring-a-sctp-endpoint)
   - [Monitoring a WebSocket endpoint](#monitoring-a-websocket-endpoint)
+  - [Monitoring an endpoint using gRPC](#monitoring-an-endpoint-using-grpc)
   - [Monitoring an endpoint using ICMP](#monitoring-an-endpoint-using-icmp)
   - [Monitoring an endpoint using DNS queries](#monitoring-an-endpoint-using-dns-queries)
   - [Monitoring an endpoint using SSH](#monitoring-an-endpoint-using-ssh)
@@ -2956,6 +2957,45 @@ shows whether the connection was successfully established. You can use Go templa
 syntax.
 
 
+### Monitoring an endpoint using gRPC
+You can monitor gRPC services by prefixing `endpoints[].url` with `grpc://` or `grpcs://`.
+Gatus executes the standard `grpc.health.v1.Health/Check` RPC against the target.
+
+```yaml
+endpoints:
+  - name: my-grpc
+    url: grpc://localhost:50051
+    interval: 30s
+    conditions:
+      - "[CONNECTED] == true"
+      - "[BODY].status == SERVING"  # BODY is read only when referenced
+    client:
+      timeout: 5s
+```
+
+For TLS-enabled servers, use `grpcs://` and configure client TLS if necessary:
+
+```yaml
+endpoints:
+  - name: my-grpcs
+    url: grpcs://example.com:443
+    conditions:
+      - "[CONNECTED] == true"
+      - "[BODY].status == SERVING"
+    client:
+      timeout: 5s
+      insecure: false          # set true to skip cert verification (not recommended)
+      tls:
+        certificate-file: /path/to/cert.pem      # optional mTLS client cert
+        private-key-file: /path/to/key.pem       # optional mTLS client key
+```
+
+Notes:
+- The health check targets the default service (`service: ""`). Support for a custom service name can be added later if needed.
+- The response body is exposed as a minimal JSON object like `{"status":"SERVING"}` only when required by conditions or suite store mappings.
+- Timeouts, custom DNS resolvers and SSH tunnels are honored via the existing [`client` configuration](#client-configuration).
+
+
 ### Monitoring an endpoint using ICMP
 By prefixing `endpoints[].url` with `icmp://`, you can monitor endpoints at a very basic level using ICMP, or more
 commonly known as "ping" or "echo":