docs: improving the front page

removed the caveat that the 3.x-documentation is AI-generated.  I think I've done relatively good QA and rewriting efforts on this

Author: tobixen

docs/source/index.rst

@@ -4,11 +4,6 @@
 
 This is the Python CalDAV client library, making communication with calendaring servers easy.
 
-NOTE: version 3 introduces quite some new API.  The documentation has been AI-maintained to reflect this, causing two potential problems:
-
-* The quality of the doc may be varying.  I will get back to it and do proper QA on the documentation when I have my hands free.
-* This is the v3-documentation.  If you're stuck on v2, then quite some of the instructions in this documentation will not work for you.
-
 Upgrading from v2?  See :doc:`v3-migration`.
 
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