Create rule for the word 'currently'

Test for the use of the word 'currently,' because documentation
only talks about the now, without reference to points in the future.

doc/.vale/gitlab/CurrentStatus.yml

+---
+# Suggestion: gitlab.CurrentStatus
+# Checks for words that indicate a product or feature may change in the future.
+#
+# For a list of all options, see https://errata-ai.github.io/vale/styles/
+extends: existence
+message: 'Avoid words like "%s" that promise future changes.'
+level: suggestion
+ignorecase: true
+link: https://docs.gitlab.com/ee/development/documentation/styleguide.html#language-to-avoid
+tokens:
+  - currently