Translation string needs improvement

[fbausch]

Hi,

the code uses the string Showing revisions of, looks up the translation for the configured language, and appends some label to the translation. See https://github.com/nextcloud/passman/blob/6fe7ff44728446d1dfca6b3226063e4b64077240/templates/views/credential_revisions.html#L13

However, this leads to issues when translating the string to a language where the position of the "label" is not at the end of the string but somewhere else. In this case, the string cannot be translated correctly.

The translation string should be Showing revisions of {labelPlaceholder} or something similar.