Clarify crosslink to variable operators

doc/ci/yaml/README.md

@@ -1200,8 +1200,8 @@ or excluded from a pipeline. In plain English, `if` rules can be interpreted as
 `rules:if` differs slightly from `only:variables` by accepting only a single
 expression string per rule, rather than an array of them. Any set of expressions to be
 evaluated can be [conjoined into a single expression](../variables/README.md#conjunction--disjunction)
-by using `&&` or `||`, and use
-the [variable matching syntax](../variables/README.md#syntax-of-environment-variable-expressions).
+by using `&&` or `||`, and the [variable matching operators (`==`, `!=`, `=~` and `!~`)](../variables/README.md#syntax-of-environment-variable-expressions).
+
 Unlike variables in [`script`](../variables/README.md#syntax-of-environment-variables-in-job-scripts)
 sections, variables in rules expressions are always formatted as `$VARIABLE`.