Fix typos (jupyter#7472)

Author: algonell

CHANGELOG.md

@@ -2533,7 +2533,7 @@ installing on Windows ([3220](https://github.com/jupyter/notebook/pull/3220)).
 
 ## 5.3.0
 
-This release introduces a couple noteable improvements, such as terminal
+This release introduces a couple notable improvements, such as terminal
 support for Windows and support for OS trash (files deleted from the
 notebook dashboard are moved to the OS trash vs. deleted permanently).
 

docs/source/migrating/custom-themes.md

@@ -8,7 +8,7 @@ This is for example the case for community contributed themes such as [jupyter-t
 
 Fortunately installing a custom theme for Notebook 7 is very easy. It is the same process as installing a regular extension.
 
-For exampe let's say you want to install the [JupyterLab Night](https://github.com/martinRenou/jupyterlab-night) theme. You can do so by running the following command:
+For example let's say you want to install the [JupyterLab Night](https://github.com/martinRenou/jupyterlab-night) theme. You can do so by running the following command:
 
 ```bash
 pip install jupyterlab-night