DOC: Update Release-note

RELEASE_NOTES.txt

+OTB-v 8.0.1 - Changes since version 8.0.0 (April 27th, 2022)
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+
+Bugs fixed:
+
+   * !906: Add missing parts of python API by Julien Osman
+
+CI:
+
+   * !911: Upgrade zlib to version 1.2.12 and GDAL to version 3.4.2 by Julien Osman
+  
+Documentation:
+
+   * !911: Fix formating issue by Julien Osman
+   * !911: Update warning message about python version by Julien Osman
+
+
 OTB-v 8.0.0 - Changes since version 7.4.0 (March 22th, 2022)
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