solution: docs for health check

docs/reference-configuration.adoc

@@ -31,6 +31,14 @@ monitoring:
     port: 8081
     path: /metrics
 
+health:
+  port: 8082
+  host: 127.0.0.1
+  path: /health
+  blockchains:
+   - chain: ethereum
+     min-availability: 1
+
 cache:
   redis:
     enabled: true
@@ -164,6 +172,10 @@ See <<tls>> section
 | Setup Prometheus monitoring.
 See <<monitoring>> section
 
+| `health`
+|
+| Setup Health Check endpoint See <<health>> section
+
 | `proxy`
 |
 | Setup HTTP proxy that emulates all standard JSON RPC requests.
@@ -285,6 +297,52 @@ _Reserved for future use_, in case of multiple different types of endpoints.
 
 |===
 
+[#health]
+== Health Check endpoint
+
+[source,yaml]
+----
+health:
+  port: 8082
+  host: 127.0.0.1
+  path: /health
+  blockchains:
+    - chain: ethereum
+      min-available: 2
+    - chain: bitcoin
+      min-available: 1
+----
+
+[cols="2a,2a,5"]
+|===
+| Option | Default Value | Description
+
+| `port`
+| `8082`
+| HTTP port to bind the server
+
+| `host`
+| `127.0.0.1`
+| HTTP host to bind the server
+
+| `path`
+| `/health`
+| HTTP path to respond on requests
+
+| `blockchains`
+|
+| List of blockchains that must be available to consider the server _healthy_
+
+| `[blockchain].chain`
+|
+| Blockchain id
+
+| `[blockchain].min-available`
+| 1
+| How many _available_ upstreams for the blockchain is required to pass
+
+|===
+
 [#proxy]
 == Proxy config