add disclaimer for generated files #917

Job	Run time
Test install with generated cython files	3m 29s
Test installation using system supplied libs	3m 12s
Test installation using newest version of Taskflow	3m 16s
Python 3.9	5m 16s
Test sse2 code on Linux (gcc)	6m 32s
Python 3.9	8m 28s
Python 3.9	6m 13s
Python 3.10	4m 53s
Python 3.10	7m 17s
Python 3.10	8m 10s
Python 3.11	4m 59s
Python 3.11	7m 32s
Python 3.11	7m 14s
Python 3.12	5m 4s
Python 3.12	8m 46s
Python 3.12	9m 42s
Python 3.13	5m 12s
Python 3.13	9m 51s
Python 3.13	8m 25s
	2h 3m 31s

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