Add .ftlh as file extension

[mimatn]

Following this issue, Spring Boot 2.2 changed the freemarker file extension from .ftl to .ftlh.

Please add .ftlh as a file extension managed by this plugin, so that the renamed files automatically get the correct syntax highlight.

Thank you very much for the excellent extension.

[valentinoPereira]

You can configure file association for your .ftlh files to use Freemarker highlighting!

Steps:

1. Open your .ftlh file in vscode
2. Click on the select language mode option on bottom right status bar of vscode
3. A search bar with options will open, select the second option " Configure file association for '.ftlh'
4. Select "Freemarker" from the options which appear

Done!