tau spacing

Co-authored-by: Hugo van Kemenade <[email protected]>

Author: AA-Turner

Doc/library/cmath.rst

@@ -81,7 +81,7 @@ the function is then applied to the result of the conversion.
 --------------------------------------------------------------------------------------------------
 :data:`pi`                                            *π* = 3.141592...
 :data:`e`                                             *e* = 2.718281...
-:data:`tau`                                           *τ* = 2 *π* = 6.283185...
+:data:`tau`                                           *τ* = 2\ *π* = 6.283185...
 :data:`inf`                                           Positive infinity
 :data:`infj`                                          Pure imaginary infinity
 :data:`nan`                                           "Not a number" (NaN)