use only generic connection in examples (#632)

docs/04-upstream-config.adoc

@@ -59,8 +59,7 @@ cluster:
       options:
         disable-validation: true
       connection:
-        ethereum-pos:
+        generic:
-            execution:
           rpc:
             url: "https://lb.drpc.org/ogrpc?network=ethereum&dkey=${DRPC_KEY}"
           ws:

docs/reference-configuration.adoc

@@ -110,8 +110,7 @@ cluster:
         disabled:
           - name: "admin_shutdown"
       connection:
-        ethereum-pos:
+        generic:
-            execution:
           rpc:
             url: "http://localhost:8545"
           ws:
@@ -125,8 +124,7 @@ cluster:
       options:
         disable-validation: true
       connection:
-        ethereum-pos:
+        generic:
-            execution:
           rpc:
             url: "https://mainnet.infura.io/v3/fa28c968191849c1aff541ad1d8511f2"
             basic-auth:
@@ -610,8 +608,7 @@ cluster:
     - id: local
       chain: ethereum
       connection:
-        ethereum-pos:
+        generic:
-            execution:
           rpc:
             url: "http://localhost:8545"
           ws:
@@ -657,8 +654,7 @@ configuration, and may be omitted for most of the situations.
     disabled:
       - name: "admin_shutdown"
   connection:
-    ethereum-pos:
+    generic:
-      execution:
       rpc:
         url: "http://localhost:8545"
       ws:
@@ -722,9 +718,9 @@ See xref:09-quorum-and-selectors.adoc[Quorum and Selectors]
 `not_empty` - accept not _null_ value, otherwise retry another upstream;
 `not_lagging` - accept response only from a fully synced upstream.
 
-| `connection.ethereum-pos`
+| `connection.generic`
 | yes
-| Connection configuration for Ethereum API of PoS network
+| Generic connection configuration for most of networks e.g. Ethereum
 
 | `connection.bitcoin`
 | yes