docs: typos in example notebooks corrected.

examples/02_correlators.ipynb

@@ -242,7 +242,7 @@
    "id": "4a9d13b2",
    "metadata": {},
    "source": [
-    "We can also use the priodicity of the lattice in order to obtain the cosh effective mass"
+    "We can also use the periodicity of the lattice in order to obtain the cosh effective mass"
    ]
   },
   {
@@ -387,8 +387,7 @@
    "source": [
     "## Missing Values \n",
     "\n",
-    "Apart from the build-in functions, there is another reason, why one should use a **Corr** instead of a list of **Obs**. \n",
-    "Missing values are handled for you. \n",
+    "Apart from the build-in functions, another benefit of using ``Corr`` objects is that they can handle missing values. \n",
     "We will create a second correlator with missing values. "
    ]
   },
@@ -459,18 +458,6 @@
     "The important thing is that, whatever you do, correlators keep their length **T**. So there will never be confusion about how you count timeslices. You can also take a plateau or perform a fit, even though some values might be missing."
    ]
   },
-  {
-   "cell_type": "code",
-   "execution_count": 18,
-   "id": "f3c4609c",
-   "metadata": {},
-   "outputs": [],
-   "source": [
-    "assert first_derivative.T == my_correlator.T == len(first_derivative.content) == len(my_correlator.content)\n",
-    "assert first_derivative.content[0] is None\n",
-    "assert first_derivative.content[-1] is None"
-   ]
-  },
   {
    "cell_type": "markdown",
    "id": "7fcbcac4",