Change language for "Custom" option in the Background Settings menu

[rudokemper]

Describe the idea
During Mapeo QA Manual Testing, the following desired enhancement was filed by @aliya-ryan:

The language in the box for "Custom Background Settings" could change. Call it "Custom Background Map" and then put actual instructions in the box of how to get your offline map appear.

The following is a proposed set of changes. These will have to be implemented and translated via CrowdIn since this text content is localized.

• Change the layer label to Custom Background Map
• Change the layer tooltip to Edit custom background map
• Change the modal title to Custom Background Map Settings
• Change the modal description text to:

If you have map tiles that you would like to use as your custom background map in Mapeo Territory, you can enter a URL path for those tiles using the box below.

If these are offline tiles that you have imported into Mapeo or placed in the Mapeo systems folder, you can use the following format to access them:
http://localhost:5005/styles/default/tiles/tilename/{zoom}/{x}/{y}

Change the tilename to the name of your tileset (which can be either a directory or an ASAR file). If it doesn't work, it's possible that your tileset is not located in the /styles/default/tiles/ directory, in which case you need to adapt the path to the exact location of your tileset.

If your tiles are raster tiles in a .jpg or .png format, you need to add that at the end of your URL path, by adding .jpg or .png after {y}. Also, change the port (the number after localhost:) from 5005 to 5000.

For more information, visit the Mapeo documentation at https://docs.mapeo.app/