Added map, map_values

pkg/yqlib/doc/headers/map.md

@@ -0,0 +1,3 @@
+# Map
+
+Maps values of an array. Use `map_values` to map values of an object.

pkg/yqlib/doc/map.md

@@ -0,0 +1,40 @@
+# Map
+
+Maps values of an array. Use `map_values` to map values of an object.
+
+## Map array
+Given a sample.yml file of:
+```yaml
+- 1
+- 2
+- 3
+```
+then
+```bash
+yq eval 'map(. + 1)' sample.yml
+```
+will output
+```yaml
+- 2
+- 3
+- 4
+```
+
+## Map object values
+Given a sample.yml file of:
+```yaml
+a: 1
+b: 2
+c: 3
+```
+then
+```bash
+yq eval 'map_values(. + 1)' sample.yml
+```
+will output
+```yaml
+a: 2
+b: 3
+c: 4
+```
+