Move Values.md into Syntax.md, fixes documentationjs#17

* Removed table showing correspondence between JS operators and Prelude
  operators, as it suggests that these operators are built in to the
  language.
* Fix misleading section heading 'user-defined operators' for the same
  reason
* Moved the rest of language/Values.md into language/Syntax.md as
  everything that was left was really about syntax.
* Update operator definition example to be more self-contained.

Author: hdgarrood

language/README.md

@@ -36,10 +36,9 @@ The full language reference continues below:
 
 1. [Types](Types.md)
 2. [Syntax](Syntax.md)
-3. [Values](Values.md)
-4. [Type Classes](Type-Classes.md)
-5. [Pattern Matching](Pattern-Matching.md)
-6. [Modules](Modules.md)
-7. [FFI](FFI.md)
-8. [Records](Records.md)
-9. [Differences from Haskell](Differences-from-Haskell.md)
+3. [Type Classes](Type-Classes.md)
+4. [Pattern Matching](Pattern-Matching.md)
+5. [Modules](Modules.md)
+6. [FFI](FFI.md)
+7. [Records](Records.md)
+8. [Differences from Haskell](Differences-from-Haskell.md)