Update iproto replication doc

doc/reference/internals/iproto/images/repl_fetch_snapshot_request.puml

@@ -0,0 +1,18 @@
+@startuml
+
+skinparam {
+    HyperlinkColor #0077FF
+    FontColor #313131
+    BorderColor #313131
+    BackgroundColor transparent
+}
+
+json "**IPROTO_FETCH_SNAPSHOT**" as fetch_snapshot_request {
+    "Size": "MP_UINT",
+    "Header": {
+      "[[https://tarantool.io/en/doc/latest/reference/internals/iproto/keys IPROTO_REQUEST_TYPE]]": "IPROTO_FETCH_SNAPSHOT",
+      "[[https://tarantool.io/en/doc/latest/reference/internals/iproto/keys IPROTO_SYNC]]": "MP_UINT"
+    }
+}
+
+@enduml

doc/reference/internals/iproto/images/repl_join_meta.puml

@@ -0,0 +1,18 @@
+@startuml
+
+skinparam {
+    HyperlinkColor #0077FF
+    FontColor #313131
+    BorderColor #313131
+    BackgroundColor transparent
+}
+
+json "**IPROTO_JOIN_META**" as join_meta_request {
+    "Size": "MP_UINT",
+    "Header": {
+      "[[https://tarantool.io/en/doc/latest/reference/internals/iproto/keys IPROTO_REQUEST_TYPE]]": "IPROTO_JOIN_META",
+      "[[https://tarantool.io/en/doc/latest/reference/internals/iproto/keys IPROTO_SYNC]]": "MP_UINT"
+    }
+}
+
+@enduml

doc/reference/internals/iproto/images/repl_join_request.puml

@@ -14,7 +14,8 @@ json "**IPROTO_JOIN**" as join_request {
       "[[https://tarantool.io/en/doc/latest/reference/internals/iproto/keys IPROTO_SYNC]]": "MP_UINT"
     },
     "Body": {
-      "[[https://tarantool.io/en/doc/latest/reference/internals/iproto/keys IPROTO_INSTANCE_UUID]]": "MP_STR – UUID of this instance"
+      "[[https://tarantool.io/en/doc/latest/reference/internals/iproto/keys IPROTO_INSTANCE_UUID]]": "MP_STR – UUID of this instance",
+      "[[https://tarantool.io/en/doc/latest/reference/internals/iproto/keys IPROTO_SERVER_VERSION]]": "MP_UINT – replica's version"
     }
 }
 

doc/reference/internals/iproto/images/repl_join_response.puml

@@ -7,7 +7,7 @@ skinparam {
     BackgroundColor transparent
 }
 
-json "**Response to IPROTO_JOIN**" as join_response {
+json "**Response to IPROTO_JOIN/IPROTO_FETCH_SNAPSHOT**" as join_response {
     "Size": "MP_UINT",
     "Header": {
       "[[https://tarantool.io/en/doc/latest/reference/internals/iproto/keys IPROTO_REQUEST_TYPE]]": "IPROTO_OK",