migrate docs to mdx

website/docs/language/functions/keys.mdx

@@ -0,0 +1,26 @@
+---
+page_title: keys - Functions - Configuration Language
+description: The keys function returns a list of the keys in a given map.
+---
+
+# `keys` Function
+
+`keys` takes a map and returns a list containing the keys from that map.
+
+The keys are returned in lexicographical order, ensuring that the result will
+be identical as long as the keys in the map don't change.
+
+## Examples
+
+```
+> keys({a=1, c=2, d=3})
+[
+  "a",
+  "c",
+  "d",
+]
+```
+
+## Related Functions
+
+* [`values`](/language/functions/values) returns a list of the _values_ from a map.