Fix of two typos (#158)

* fix typo

Signed-off-by: retrooper <retrooperdev@gmail.com>

* another typo fixed

Signed-off-by: retrooper <retrooperdev@gmail.com>

---------

Signed-off-by: retrooper <retrooperdev@gmail.com>

Author: retrooper

docs/source/ordinal.ipynb

@@ -472,7 +472,7 @@
    "source": [
     "It looks like players at index 1, 2 and 3, they have almost indentical means. So they overlap each other quite a bit. But if you have a keen eye, you will notice that the lavender line representing player at index 2 has a higher peak (also known as negative kurtosis in literature). This means the system is overall more confident in player at index 2's skill.\n",
     "\n",
-    "By default the value of an ordinal is determined by the fomula '$μ - 3σ$' which by the [empirical rule](https://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule) only allows for the system to be confident upto 99.7%. As such when $σ$ is still high such as when players have played few games will lead to the overal ordinal fluctuating.\n",
+    "By default the value of an ordinal is determined by the formula '$μ - 3σ$' which by the [empirical rule](https://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule) only allows for the system to be confident up to 99.7%. As such when $σ$ is still high such as when players have played few games will lead to the overall ordinal fluctuating.\n",
     "\n",
     "You can curtail this effect for large numbers of matches by using the \"Additive Dynamics Factor\" $\\tau$ (parameter \"tau\") into the models of this library in combination with the `limit_sigma` parameter."
    ],