fix plot doc

Author: Badr-MOUFAD

examples/plot_survival_analysis.py

@@ -69,6 +69,7 @@
 
 # skglm internals: init datafit and penalty
 datafit = Cox()
+datafit.initialize(X, y)
 penalty = L1(alpha)
 
 # init solver
@@ -228,6 +229,7 @@
 
 # ensure using Efron estimate
 datafit = Cox(use_efron=True)
+datafit.initialize(X, y)
 
 # solve the problem
 solver = ProxNewton(fit_intercept=False, max_iter=50)