This plugin simply replaces a default feature of the suggestion box which appears after writing a "|" in a link with a new suggestion box which allows you to add the display text you type after the "|" in a link as a new alias.
I found myself writing notes and defining aliases, but forgetting certain aliases so whenever I went to write links to those notes with specific display texts, I would find that I would have to reopen that other note and go and define that alias. This plugin helps you skip that part, so whenever you write a display text that isn't already defined as an alias, it just creates a new alias in that note for you with the display text you have written (all the text after the "|" in an internal link).
Just enable the plugin, and wherever you type "[[X|Y" (where X is the name of the note you're linking to, and Y is the display text you're going to use), a suggestion should appear, click it or press enter and the plugin will automatically add whatever you wrote as display text as a new alias in the note you were referencing.