RCFilters UI: Correct full coverage message

Not all groups have this behavior, so it's not accurate to say that "Selecting all filters in *A* group" behaves this way. Instead say "all filters in *THIS* group". Change-Id: Iaa92db76b27a2b0175e1ba1c71d1ef087857e87e

Author: catrope

languages/i18n/en.json

@@ -1391,7 +1391,7 @@
 "rcfilters-filterlist-noresults": "No filters found",
 "rcfilters-noresults-conflict": "No results found because the search criteria are in conflict",
 "rcfilters-state-message-subset": "This filter has no effect because its results are included with those of the following, broader {{PLURAL:$2|filter|filters}} (try highlighting to distinguish it): $1",
-"rcfilters-state-message-fullcoverage": "Selecting all filters in a group is the same as selecting none, so this filter has no effect. Group includes: $1",
+"rcfilters-state-message-fullcoverage": "Selecting all filters in this group is the same as selecting none, so this filter has no effect. Group includes: $1",
 "rcfilters-filtergroup-authorship": "Contribution authorship",
 "rcfilters-filter-editsbyself-label": "Changes by you",
 "rcfilters-filter-editsbyself-description": "Your own contributions.",