feat: added note about GT tuple

Author: TimD1

pysam/libcbcf.pyx

@@ -3464,6 +3464,9 @@ cdef class VariantRecordSample(object):
                  'VAF': (1.0,)},
                  'PS': None
              }
+
+       Note:
+         When using this API, the "GT" value must be provided as a tuple (0, 1) and not a string "0/1".
     """
     def __init__(self, *args, **kwargs):
         raise TypeError('this class cannot be instantiated from Python')