Fix typo in cholesky_factor_cov type name

Author: jachymb

src/stan-users-guide/complex-numbers.qmd

@@ -117,7 +117,7 @@ can be expressed as follows.
 ```stan
 complex z;
 vector[2] mu;
-cholesky_cov[2] L_Sigma;
+cholesky_factor_cov[2] L_Sigma;
 // ...
 [get_real(z), get_imag(z)]' ~ multi_normal_cholesky(mu, L_Sigma);
 ```