Clarify documentation on how /etc/borgmatic.d/ configuration files are interpreted.

docs/how-to/make-per-application-backups.md

@@ -22,6 +22,11 @@ When you set up multiple configuration files like this, borgmatic will run
 each one in turn from a single borgmatic invocation. This includes, by
 default, the traditional `/etc/borgmatic/config.yaml` as well.
 
+Each configuration file is interpreted independently, as if you ran borgmatic
+for each configuration file one at a time. In other words, borgmatic does not
+perform any merging of configuration files by default. If you'd like borgmatic
+to merge your configuration files, see below about configuration includes.
+
 And if you need even more customizability, you can specify alternate
 configuration paths on the command-line with borgmatic's `--config` option.
 See `borgmatic --help` for more information.

docs/how-to/set-up-backups.md

@@ -3,15 +3,11 @@ title: How to set up backups with borgmatic
 ---
 ## Installation
 
-To get up and running, first [install
-Borg](https://borgbackup.readthedocs.io/en/stable/installation.html), at
-least version 1.1.
+First, [install
+Borg](https://borgbackup.readthedocs.io/en/stable/installation.html), at least
+version 1.1.
 
-By default, borgmatic looks for its configuration files in `/etc/borgmatic/`
-and `/etc/borgmatic.d/`, where the root user typically has read access.
-
-So, to download and install borgmatic as the root user, run the following
-commands:
+Then, download and install borgmatic by running the following command:
 
 ```bash
 sudo pip3 install --user --upgrade borgmatic