Update changelog for upcoming 0.26.1

[evgenykochetkov]

Bug fixes

• [ide] Fix a bug that caused "Save As" command to be invoked instead of "Save" after opening a project file (Fix updating of project path while opening IDE via associated files #1615)
• [ide] Make message about available updates harder to miss (Make persistent update available message #1614)
• [ide] Fix an error caused by presence of "stale" patch.cpp implementations in patch folder (When flattening, check that patch is leaf by presence of niix marker instead of attachment #1616)
• [ide] Do not save autogenerated patches (like terminals for custom types) to file system (Do not save terminal patches for custom types #1603)