tweak to Readme

Dependencies

• [2] BYG5CEMV support for naming points
• [3] 242L3OQX bugfix: ensure Cursor_line is always on a text line
• [4] IDGP4BJZ new known issue with drawings
• [*] FS2ITYYH record a known issue

Change contents

• replacement in README.md at line 90
  [3.21]→[2.2158:2256](∅→∅)
  − * No clipping yet for drawings. In particular, circles and point labels can

  − overflow a drawing.
  [3.21]

  [2.2256]
  + * No clipping yet for drawings. In particular, circles/squares/rectangles and

  + point labels can overflow a drawing.