Clarify it's the "path" of the error that matters, not the position that re-raised it

Author: benjie

spec/Section 6 -- Execution.md

@@ -922,8 +922,8 @@ result_.
 
 If a _response position_ resolves to {null} because of an execution error which
 has already been added to the {"errors"} list in the _execution result_, the
-{"errors"} list must not be further affected. That is, only one error should be
-added to the errors list per _response position_.
+{"errors"} list must not be further affected. That is, each error added to the
+errors list during execution must have a unique _response path_.
 
 Since `Non-Null` response positions cannot be {null}, execution errors are
 propagated to be handled by the parent _response position_. If the parent

spec/Section 7 -- Response.md

@@ -70,7 +70,7 @@ The _request error result_ map must not contain an entry with key {"data"}.
 The _request error result_ map may also contain an entry with key `extensions`.
 The value of this entry is described in the "Extensions" section.
 
-### Response Position
+### Response Path
 
 <a name="sec-Path">
   <!-- Legacy link, this section was previously titled "Path" -->