Merge branch 'sg/index-format-doc-update'

Docfix.

* sg/index-format-doc-update:
  index-format.txt: remove outdated list of supported extensions
diff --git a/Documentation/technical/index-format.txt b/Documentation/technical/index-format.txt
index 65da0da..f691c20 100644
--- a/Documentation/technical/index-format.txt
+++ b/Documentation/technical/index-format.txt
@@ -26,8 +26,6 @@
      Extensions are identified by signature. Optional extensions can
      be ignored if Git does not understand them.
 
-     Git currently supports cache tree and resolve undo extensions.
-
      4-byte extension signature. If the first byte is 'A'..'Z' the
      extension is optional and can be ignored.