style: add additional details on thermo defaults

prymer/primer3/primer3_parameters.py

@@ -195,7 +195,10 @@ class ProbeParameters:
     If they are not provided, `probe_max_self_any_thermo`, `probe_max_self_end_thermo`, and
     `probe_max_hairpin_thermo` will be set to default values as specified in the Primer3 manual.
     The default value is 10 degrees lower than the minimal melting temperature specified for
-    probe design.
+    probe design (i.e., when not provided, values are specified relative to the probe design).
+    If these values are provided, users should provide the absolute value of the
+    melting temperature threshold (i.e., when provided, values should be specified as independent
+    of probe design.)
 
     """