fix doctest

Author: Xavier Caruso

src/sage/rings/function_field/drinfeld_modules/drinfeld_module.py

@@ -2082,9 +2082,9 @@ def frobenius_relative(self, n=1):
         Return the `n`-th iterate relative Frobenius of this Drinfeld module.
 
         By definition, the relative Frobenius is the isogeny represented by
-        the Ore polynomial `tau^d` where `d` is the degree of the characteristic
+        the Ore polynomial `\tau^d` where `d` is the degree of the characteristic
         of this Drinfeld module (which is also the degree of `\gamma(T)` over
-        `\mathbb F_q`, where `\gamma` is the base morphism `\mathbb F_q[T] \to F`).
+        `\mathbb F_q`, where `\gamma` is the base morphism `\mathbb F_q[T] \to K`).
 
         INPUT:
 
@@ -2107,7 +2107,7 @@ def frobenius_relative(self, n=1):
               To:   Drinfeld module defined by T |--> (3*z^2 + 1)*τ^2 + (3*z^2 + 1)*τ + 1
               Defn: τ^2
 
-        If `F` is finite and `n` is the degree of `F` over `\FF_q(\gamma(T))`,
+        If `K` is finite and `n` is the degree of `K` over `\mathbb F_q(\gamma(T))`,
         we obtain the Frobenius endomorphism::
 
             sage: phi.frobenius_relative(3) == phi.frobenius_endomorphism()