changes.txt: update with current fixes, assuming next release has mupdf-1.26.11 or later.

Author: julian-smith-artifex-com

changes.txt

@@ -4,8 +4,12 @@ Change Log
 
 **Changes in version 1.26.6**
 
+* Use MuPDF-1.26.11.
+
 * Fixed issues:
 
+  * **Fixed** `4699 <https://github.com/pymupdf/PyMuPDF/issues/4699>`_: cannot find ExtGState resource
+  * **Fixed** `4712 <https://github.com/pymupdf/PyMuPDF/issues/4712>`_: Crash with "corrupted double-linked list"
   * **Fixed** `4742 <https://github.com/pymupdf/PyMuPDF/issues/4742>`_: 'Rect' object has no attribute 'get_area'
   * **Fixed** `4746 <https://github.com/pymupdf/PyMuPDF/issues/4746>`_: Document.__init__() got an unexpected keyword argument 'encoding'