Updated information about builtin functions.

src/content/docs/references/docs/builtins.md

@@ -9,7 +9,7 @@ name prefix.
 
 ## Builtin constants
 
-These can all safely be used by the user.
+These constants are generated by the compiler and can safely be used by the user.
 
 #### $$BENCHMARK_NAMES
 An array of names of the benchmark functions.
@@ -46,22 +46,26 @@ The current module name.
 The current time.
 
 
-## Builtin functions
+## Compiler builtin functions
 
-These functions are *not guaranteed* to exist on all platforms. They are intended for standard library
-internal use, and typically the standard library has macros that wrap these builtins, so they should not be used on its own.
+The `$$` namespace defines *compiler builtin functions*. 
+These special functions are __not guaranteed__ to exist on 
+all platforms, and are ways to wrap compiler implemented, optimized implementations
+of some particular functionality. They are mainly intended for standard 
+library *internal* use. The standard library have macros 
+that wrap these builtins, so they should normally not be used on their own. 
 
 #### $$trap
 
-Emits a trap instruction.
+Emits a trap instruction. 
 
 #### $$unreachable
 
 Inserts an "unreachable" annotation.
 
 #### $$stacktrace
 
-Returns the current "callstack" reference if available. Compiler dependent.
+Returns the current "callstack" reference if available. OS and compiler dependent.
 
 #### $$volatile_store