Organize terminal emulators under Terminal Apps

[xaocon]

There were several terminal emulators in the command-line-apps.md file making them difficult to find. I've moved them to the Terminal Apps section in the main README. In addition to moving the links, the section was made to adhere to the alphabetic ordering rules. Links were only moved, not added or removed.

This commit does not update the Chinese language versions of files.

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