Include {data.table} example in redundant_equals_linter() docs (#2659)

Author: IndrajeetPatil

R/redundant_equals_linter.R

@@ -19,6 +19,11 @@
 #'   linters = redundant_equals_linter()
 #' )
 #'
+#' lint(
+#'   text = "dt[is_tall == FALSE, y]",
+#'   linters = redundant_equals_linter()
+#' )
+#'
 #' # okay
 #' lint(
 #'   text = "if (any(x)) 1",
@@ -30,6 +35,12 @@
 #'   linters = redundant_equals_linter()
 #' )
 #'
+#' # in `{data.table}` semantics, `dt[x]` is a join, `dt[(x)]` is a subset
+#' lint(
+#'   text = "dt[(!is_tall), y]",
+#'   linters = redundant_equals_linter()
+#' )
+#'
 #' @evalRd rd_tags("redundant_equals_linter")
 #' @seealso
 #' - [linters] for a complete list of linters available in lintr.