[MINOR] Fix typo in 'hypot' docstring

Minor typo:  docstring for pyspark.sql.functions: hypot has extra characters

N/A

Author: Tristan Reid <treid@netflix.com>

Closes #11616 from tristanreid/master.

python/pyspark/sql/functions.py

@@ -142,7 +142,7 @@ def _():
 _binary_mathfunctions = {
     'atan2': 'Returns the angle theta from the conversion of rectangular coordinates (x, y) to' +
              'polar coordinates (r, theta).',
-    'hypot': 'Computes `sqrt(a^2^ + b^2^)` without intermediate overflow or underflow.',
+    'hypot': 'Computes `sqrt(a^2 + b^2)` without intermediate overflow or underflow.',
     'pow': 'Returns the value of the first argument raised to the power of the second argument.',
 }