Add reference for JsLessThan and JsLessThanOrEqual (microsoft#43)

This PR updates the documents for chakra-core/ChakraCore#3931.

Author: xiaoyinl

JavaScript-Runtime-(JSRT)-Reference.md

@@ -125,6 +125,8 @@ References of JSRT typedefs, constants, enumerations and APIs.
 * [[JsInstanceOf]]
 * [[JsIntToNumber]]
 * [[JsIsRuntimeExecutionDisabled]]
+* [[JsLessThan]]
+* [[JsLessThanOrEqual]]
 * [[JsNumberToDouble]]
 * [[JsNumberToInt]]
 * [[JsParse]]

reference/JsLessThan.md

@@ -0,0 +1,20 @@
+Determine if one JavaScript value is less than another JavaScript value.
+### Syntax
+```
+CHAKRA_API
+    JsLessThan(
+        _In_ JsValueRef object1,
+        _In_ JsValueRef object2,
+        _Out_ bool *result);
+```
+### Parameters
+* __object1__: The first object to compare.
+* __object2__: The second object to compare.
+* __result__: Whether object1 is less than object2.
+
+### Return Value
+The code **JsNoError** if the operation succeeded, a failure code otherwise.
+### Remarks
+Requires an active script context.
+
+This function is equivalent to the **\<** operator in Javascript.

reference/JsLessThanOrEqual.md

@@ -0,0 +1,20 @@
+Determine if one JavaScript value is less than or equal to another JavaScript value.
+### Syntax
+```
+CHAKRA_API
+    JsLessThanOrEqual(
+        _In_ JsValueRef object1,
+        _In_ JsValueRef object2,
+        _Out_ bool *result);
+```
+### Parameters
+* __object1__: The first object to compare.
+* __object2__: The second object to compare.
+* __result__: Whether object1 is less than or equal to object2.
+
+### Return Value
+The code **JsNoError** if the operation succeeded, a failure code otherwise.
+### Remarks
+Requires an active script context.
+
+This function is equivalent to the **\<=** operator in Javascript.