Add ability to disable default rules

if you add the following to a config file and use that to run woke, you can disable a default rule that matches the name

```yaml
rules:
  - name: whitelist
```

pkg/rule/rule.go

@@ -22,14 +22,18 @@ type Rule struct {
 }
 
 func (r *Rule) FindAllStringIndex(text string) [][]int {
+	// If no terms are provided, this essentially disables the rule
+	// which is helpful for disabling default rules. Eventually, there should be
+	// a way to disable a default rule, and then, if a rule has no Terms, it falls back to the Name.
+	if len(r.Terms) == 0 {
+		return [][]int{}
+	}
+
 	if r.re == nil {
 		r.re = regexp.MustCompile(fmt.Sprintf(`(?i)\b(%s)\b`, strings.Join(r.Terms, "|")))
 	}
-	return r.re.FindAllStringIndex(text, -1)
-}
 
-func (r *Rule) String() string {
-	return r.Name
+	return r.re.FindAllStringIndex(text, -1)
 }
 
 // Reason returns a human-readable reason for the rule violation

pkg/rule/rule_test.go

@@ -22,6 +22,9 @@ func TestRule_FindAllStringIndex(t *testing.T) {
 		got := r.FindAllStringIndex(test.text)
 		assert.Equal(t, test.expected, got)
 	}
+
+	e := Rule{Name: "rule1"}
+	assert.Equal(t, [][]int{}, e.FindAllStringIndex("rule1"))
 }
 
 func TestRule_Reason(t *testing.T) {