fix: typo in Examples

Author: chilango74

examples/04 investment portfolios with DCF.ipynb

@@ -445,8 +445,8 @@
    "execution_count": 61,
    "outputs": [],
    "source": [
-    "s = pf2.m(\n",
-    "    distr='norm',  # the rate of return distribution. Can be set to `norm` for normal distribution or `lognorm` for lognormal\n",
+    "s = pf2.monte_carlo_survival_period(\n",
+    "    distr='norm',  # the rate of return distribution. Can be set to `norm` for normal distribution, `lognorm` for lognormal or 't' for Student's\n",
     "    years=30,  # future period\n",
     "    n=100  # Number of random time series generated by Monte Carlo\n",
     ")"