Correct the hoisted export_name doc comment

The field stores the flattened name before JS identifier conversion, not
the emitted export name; the previous wording caused a consumer to use it
verbatim.

Signed-Off-By: Cristiano Calcagno <ccrisccris@gmail.com>
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PCtQiaDijUqA2fujQXvKUw

Author: cristianoc

compiler/core/js_cmj_format.ml

@@ -48,7 +48,11 @@ type keyed_cmj_values = keyed_cmj_value array
 type hoisted_export = {
   path: string list;  (** Exact source-level module path segments. *)
   export_name: string;
-      (** Flat compiler identifier used for the public JS export. *)
+      (** Flattened compiler name for the export, before JS identifier
+          conversion: the emitted export applies [Ext_ident.convert] to it
+          (a hoisted [Operator.\"+"] is stored as [Operator$+] and exported
+          as [Operator$$plus]), and so must any consumer that reconstructs
+          the JS export name. *)
 }
 
 type t = {

compiler/core/js_cmj_format.mli

@@ -63,7 +63,11 @@ type keyed_cmj_value = {
 type hoisted_export = {
   path: string list;  (** Exact source-level module path segments. *)
   export_name: string;
-      (** Flat compiler identifier used for the public JS export. *)
+      (** Flattened compiler name for the export, before JS identifier
+          conversion: the emitted export applies [Ext_ident.convert] to it
+          (a hoisted [Operator.\"+"] is stored as [Operator$+] and exported
+          as [Operator$$plus]), and so must any consumer that reconstructs
+          the JS export name. *)
 }
 
 type t = {