created better alignment for noise_power

Signed-off-by: Nick Papior <nickpapior@gmail.com>

Author: zerothi

src/sisl/io/tbtrans/tbt.py

@@ -930,8 +930,9 @@ def noise_power(self, elec_from=0, elec_to=1, kavg=True) -> ndarray:
 
         .. math::
            S(V) = \frac{2e^2}{h}\sum_k\sum_n \int\mathrm d E
-                  \big\{T_{k,n}(E)[f_L(1-f_L)+f_R(1-f_R)] +
-                        T_{k,n}(E)[1 - T_{k,n}(E)](f_L - f_R)^2\big\} w_k
+                  \big\{&T_{k,n}(E)[f_L(1-f_L)+f_R(1-f_R)] +
+           \\
+                        &T_{k,n}(E)[1 - T_{k,n}(E)](f_L - f_R)^2\big\} w_k
 
         Where :math:`f_i` are the Fermi-Dirac distributions for the electrodes.