Fix linting errors in epic_issues.md

Fix linting errors in https://docs.gitlab.com/ee/api/epic_issues.html

11:94  error  Avoid using future tense: "will result". Use present tense instead.  gitlab.FutureTense
15:60  error  Avoid using future tense: "will be". Use present tense instead.      gitlab.FutureTense

If you'd like to work on this issue, mention @msedlakjakubowski in a comment. Then, in your merge request's description, paste this issue's URL so they become linked.

Edited Dec 01, 2020 by Marcin Sedlak-Jakubowski