added path operator!

pkg/yqlib/doc/Path Operators.md

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+The path operator can be used to find the traversal paths of matching nodes in an expression. The path is returned as an array, which if traversed in order will lead to the matching node.
+## Examples
+### Map path
+Given a sample.yml file of:
+```yaml
+a:
+  b: cat
+```
+then
+```bash
+yq eval '.a.b | path' sample.yml
+```
+will output
+```yaml
+- a
+- b
+```
+
+### Array path
+Given a sample.yml file of:
+```yaml
+a:
+  - cat
+  - dog
+```
+then
+```bash
+yq eval '.a.[] | select(. == "dog") | path' sample.yml
+```
+will output
+```yaml
+- a
+- 1
+```
+
+### Print path and value
+Given a sample.yml file of:
+```yaml
+a:
+  - cat
+  - dog
+  - frog
+```
+then
+```bash
+yq eval '.a.[] | select(. == "*og") | [{"path":path, "value":.}]' sample.yml
+```
+will output
+```yaml
+- path:
+    - a
+    - 1
+  value: dog
+- path:
+    - a
+    - 2
+  value: frog
+```
+

pkg/yqlib/doc/headers/Path Operators.md

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+The path operator can be used to find the traversal paths of matching nodes in an expression. The path is returned as an array, which if traversed in order will lead to the matching node.