Document RealIntervalField default printing configuration

Author: user202729

src/sage/rings/real_mpfi.pyx

@@ -120,6 +120,26 @@ satisfying, but we have chosen the latter.
     sage: a == 2
     False
 
+Some default printing options can be set by modifying module globals::
+
+    sage: from sage.rings import real_mpfi
+    sage: x = RIF(sqrt(2), sqrt(2)+1e-10); x
+    1.4142135624?
+    sage: real_mpfi.printing_error_digits = 2
+    sage: x
+    1.414213562424?51
+    sage: real_mpfi.printing_style = 'brackets'
+    sage: x
+    [1.4142135623730949 .. 1.4142135624730952]
+    sage: real_mpfi.printing_style = 'question'; real_mpfi.printing_error_digits = 0  # revert to default
+
+The default value of using scientific notation can be configured at field construction instead::
+
+    sage: RealIntervalField(53, sci_not=False)(0.5)
+    0.50000000000000000?
+    sage: RealIntervalField(53, sci_not=True)(0.5)
+    5.0000000000000000?e-1
+
 COMPARISONS:
 
 Comparison operations (``==``, ``!=``, ``<``, ``<=``, ``>``, ``>=``)