Update documenation (#18)

Fix typo in `use_this_plugin.md`.

nomad-{{cookiecutter.plugin_name}}/docs/how_to/use_this_plugin.md

@@ -1,8 +1,8 @@
 # How to Use This Plugin
 
-This plugin can be used in a NOMAD Oasis instalation..
+This plugin can be used in a NOMAD Oasis installation.
 
-## Add This Plugin to Your NOMAD instalation
+## Add This Plugin to Your NOMAD installation
 
 Read the [NOMAD plugin documentation](https://nomad-lab.eu/prod/v1/staging/docs/plugins/plugins.html#add-a-plugin-to-your-nomad) for all details on how to deploy the plugin on your NOMAD instance.