Update docs.

spacy/tokens/span_group.pyx

@@ -158,6 +158,16 @@ cdef class SpanGroup:
             return self._concat(other)
         return NotImplemented
 
+    def __iter__(self):
+        """
+        Iterate over the spans in this SpanGroup.
+        YIELDS (Span): A span in this SpanGroup.
+
+        DOCS: https://spacy.io/api/spangroup#iter
+        """
+        for i in range(self.c.size()):
+            yield self[i]
+
     def append(self, Span span):
         """Add a span to the group. The span must refer to the same Doc
         object as the span group.
@@ -170,15 +180,6 @@ cdef class SpanGroup:
             raise ValueError(Errors.E855.format(obj="span"))
         self.push_back(span.c)
 
-    def __iter__(self):
-        """
-        Iterate over the spans in this SpanGroup.
-        YIELDS (Span): A span in this SpanGroup.
-
-        DOCS: https://spacy.io/api/spangroup#iter
-        """
-        for i in range(self.c.size()):
-            yield self[i]
 
     def extend(self, spans_or_span_group: Union[SpanGroup, Iterable["Span"]]):
         """Add multiple spans or contents of another SpanGroup to the group.

website/docs/api/spangroup.md

@@ -202,6 +202,23 @@ already present in the current span group.
 | `other`     | The span group or spans to append. ~~Union[SpanGroup, Iterable[Span]]~~ |
 | **RETURNS** | The span group. ~~SpanGroup~~                                           |
 
+## SpanGroup.\_\_iter\_\_ {#iter tag="method" new="3.5"}
+
+Iterate over the spans in this SpanGroup.
+
+> #### Example
+>
+> ```python
+> doc = nlp("Their goi ng home")
+> doc.spans["errors"] = [doc[0:1], doc[1:3]]
+> for error_span in doc.spans["errors"]:
+>     print(error_span)
+> ```
+
+| Name       | Description                         |
+| ---------- | ----------------------------------- |
+| **YIELDS** | A span in this SpanGroup.. ~~Span~~ |
+
 ## SpanGroup.append {#append tag="method"}
 
 Add a [`Span`](/api/span) object to the group. The span must refer to the same