Added XML decoder (#1044)

pkg/yqlib/doc/operators/headers/equals.md

@@ -0,0 +1,13 @@
+# Equals
+
+This is a boolean operator that will return `true` if the LHS is equal to the RHS and `false` otherwise.
+
+```
+.a == .b
+```
+
+It is most often used with the select operator to find particular nodes:
+
+```
+select(.a == .b)
+```