Fix slightly snide comment about SQLite

The original language implies that SQLite is not an "actual" database engine, which is of course not the case! SQLite is a very capable and ubiquitous database engine. It's not appropriate for many applications, though, so perhaps the document here can simply read "different" rather than "actual". I recognize this is a bit particular, but hey-- that's how I perceived the language on my first read, and I don't even particularly like (or use) SQLite anyways! I do respect the technology, though, and thought it'd be kind to change the language so as to remove all possibility of misinterpretation.

docs/tutorial/persisting-our-data/index.md

@@ -74,7 +74,7 @@ There are two main types of volumes. We will eventually use both, but we will st
 By default, the todo app stores its data in a [SQLite Database](https://www.sqlite.org/index.html) at
 `/etc/todos/todo.db`. If you're not familiar with SQLite, no worries! It's simply a relational database in 
 which all of the data is stored in a single file. While this isn't the best for large-scale applications,
-it works for small demos. We'll talk about switching this to an actual database engine later.
+it works for small demos. We'll talk about switching this to a different database engine later.
 
 With the database being a single file, if we can persist that file on the host and make it available to the
 next container, it should be able to pick up where the last one left off. By creating a volume and attaching