Add mountains to de-CH locale

[codez]

Motivation / Background

This Pull Request has been created because the mountains generator only includes Asian and American mountains. Hereby we add a list of mountains in the Swiss alps specifically for the de-CH locale.

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one change. Changes that are unrelated should be opened in separate PRs.
• Commit message has a detailed description of what changed and why. If this PR fixes a related issue include it in the commit message. Ex: [Fix #issue-number]
• Tests are added or updated if you fix a bug, refactor something, or add a feature.
• Tests and Rubocop are passing before submitting your proposed changes.

[thdaraujo]

Do you mind narrowing the list down to maybe 10-15 options?
We don't need to provide every possible option, and this would also impact locale loading time.

[thdaraujo]

Thanks for the contribution! But let's narrow this list down to fewer options.
Do you mind rebasing?

[codez]

@thdaraujo There you go. I guess it's really difficult to find a good balance between enough variation, a vast amount of topics and acceptable loading times.