Setting up Standard Notes on Linux

First, let's download Standard Notes for Linux.

Where to put the AppImage file?

Here's one way that works: Create a directory at ~/standard-notes/ and move the AppImage file there. Also, go download a PNG of the Standard Notes logo and place it in this directory.

Creating the .desktop file

If you don't yet have a .desktop file for Standard Notes, we'll create one. At ~/.local/share/applications/standard-notes.desktop paste the following:

[Desktop Entry]
Type=Application
Name=StandardNotes
Exec=/home/$USER/standard-notes/standard-notes-*-x86_64.AppImage 
Icon=/home/$USER/standard-notes/standard-notes.png
Terminal=false
Categories=Office;Notes;

Now, after a computer restart, Standard Notes should come up when you search your applications.

More on desktop files in the Arch Wiki.