help: add help entry for internals.mergestate This patch adds an entry for `internals.mergestate` as suggested by @marmoute. Most of the help text is taken from `merge.mergestate`. Differential Revision: https://phab.mercurial-scm.org/D6448 Differential Revision: https://phab.mercurial-scm.org/D6528

# See http://EditorConfig.org for the specification

root = true

[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true

[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true

[*.t]
indent_size = 2
indent_style = space
trim_trailing_whitespace = false