docs(ui): Document how KopiaUI Desktop handles multiple config files and repositories (#4049)

site/content/docs/FAQs/_index.md

@@ -20,6 +20,7 @@ weight: 55
 * [How Do I Decrease Kopia's Memory (RAM) Usage?](#how-do-i-decrease-kopias-memory-ram-usage)
 * [What are Incomplete Snapshots?](#what-are-incomplete-snapshots)
 * [What is a Kopia Repository Server?](#what-is-a-kopia-repository-server)
+* [How does the KopiaUI handle multiple repositories?](#kopiaui-and-multiple-repositories)
 
 **Is your question not answered here? Please ask in the [Kopia discussion forums](https://kopia.discourse.group/) for help!**
 
@@ -129,3 +130,11 @@ For more information on the `checkpoint interval`, please refer to the [command-
 #### What is a Kopia Repository Server?
 
 See the [Kopia Repository Server help docs](../repository-server) for more information.
+
+#### KopiaUI and Multiple Repositories
+
+When KopiaUI starts up, it will look for configuration files in Kopia's configuration directory (`%APPDATA%\kopia` on Windows; `$HOME/.config/kopia` on linux; `$HOME/Library/Application Support/kopia` on macOS).  KopiaUI will look for all files ending in `*.config` and use these configurations to determine the set of repositories to connect to.
+
+KopiaUI will always look for a `repository.config` file,  even if that file does not exist, in which case it will try to start up a connection which will never succeed.
+
+Be aware that if you create multiple config files for testing purposes, eg, `repository.orig.config`, `repository.test1.config`, `repository.test2.config`, etc., KopiaUI will try to connect to ALL of them at startup, even if they are not intended to be valid.  Thus, if you don't want KopiaUI to use a config file, make sure it ends in something other than `.config`.