Added docs on yes/no being strings in yaml spec 1.2

pkg/yqlib/doc/operators/boolean-operators.md

@@ -26,6 +26,24 @@ will output
 true
 ```
 
+## "yes" and "no" are strings
+In the yaml 1.2 standard, support for yes/no as booleans was dropped - they are now considered strings. See '10.2.1.2. Boolean' in https://yaml.org/spec/1.2.2/
+
+Given a sample.yml file of:
+```yaml
+- yes
+- no
+```
+then
+```bash
+yq '.[] | tag' sample.yml
+```
+will output
+```yaml
+!!str
+!!str
+```
+
 ## `and` example
 Running
 ```bash

pkg/yqlib/operator_booleans_test.go

@@ -12,6 +12,16 @@ var booleanOperatorScenarios = []expressionScenario{
 			"D0, P[], (!!bool)::true\n",
 		},
 	},
+	{
+		description:    "\"yes\" and \"no\" are strings",
+		subdescription: "In the yaml 1.2 standard, support for yes/no as booleans was dropped - they are now considered strings. See '10.2.1.2. Boolean' in https://yaml.org/spec/1.2.2/",
+		document:       `[yes, no]`,
+		expression:     `.[] | tag`,
+		expected: []string{
+			"D0, P[0], (!!str)::!!str\n",
+			"D0, P[1], (!!str)::!!str\n",
+		},
+	},
 	{
 		skipDoc:    true,
 		document:   "b: hi",