Correct mistake in documentation (#198)

Rochet2 · web-flow · commit ef5ceffe71ee · 2020-03-13T00:42:15.000+08:00
diff --git a/doc/embed_wamr.md b/doc/embed_wamr.md
@@ -196,7 +196,7 @@ if(buffer_for_wasm != 0)
     
     // it is runtime responsibility to release the memory,
     // unless the WASM app will free the passed pointer in its code
-    wasm_runtime_module_free(module_inst, buffer);
+    wasm_runtime_module_free(module_inst, buffer_for_wasm);
 }
 
 ```

Original file line number	Diff line number	Diff line change
`@@ -196,7 +196,7 @@ if(buffer_for_wasm != 0)`
`196`	`196`
`197`	`197`	`// it is runtime responsibility to release the memory,`
`198`	`198`	`// unless the WASM app will free the passed pointer in its code`
`199`		`- wasm_runtime_module_free(module_inst, buffer);`
	`199`	`+ wasm_runtime_module_free(module_inst, buffer_for_wasm);`
`200`	`200`	`}`
`201`	`201`
`202`	`202`	```