I read that if you create a php file and save it in the /wp-content/mu-plugins/ directory, WordPress will auto-load it.
However, I haven't yet figured it out. I don't have a folder named mu-plugins; it's just wp-content/plugins. I created a file at wp-content/plugins/echo-values.php, put a simple echo value in it and uploaded it, but I don't see the value I echoed in my source code.
I then opened wp-content/plugins/index.php and pasted in the following code:
Again, I don't see anything in my source code, so it looks like those files aren't being included. For good measure, I echoed some text in /wp-content/plugins/index.php, but I don't even see that in the source code.
Can anyone tell me the best way to include my own PHP file? It doesn't have to be in the plugins folder, though I was advised that's the best place to put it.