Minor fixes

Author: patiencedaur

doc/dev_guide/internals/iproto/images/vclock.puml

@@ -7,10 +7,10 @@ skinparam map {
     BackgroundColor transparent
 }
 
-map vclock {
-    "replica_id1" => "LSN1",
-    "replica_id2" => "LSN2",
-    "..." => "..."
+map "**vclock**" as vclock {
+    replica_id1 => LSN1
+    replica_id2 => LSN2
+    ... => ...
 }
 
 @enduml

doc/dev_guide/internals/iproto/images/vclock.svg

@@ -4,7 +4,7 @@
 Keys used in requests and responses
 ===================================
 
-This section describes ``iproto`` keys contained in iproto requests and responses.
+This section describes ``iproto`` keys contained in requests and responses.
 The keys are Tarantool constants that are either defined or mentioned in the
 `iproto_constants.h file <https://github.com/tarantool/tarantool/blob/master/src/box/iproto_constants.h>`_.