docs(readme): add known issue about #47 to README.md

Author: teppeis

README.md

@@ -21,6 +21,10 @@ Simple API to compile TypeScript code string to JavaScript. That's all!
 * TypeScript v1.5 has [ts.transpile()](https://github.com/Microsoft/TypeScript/wiki/Using-the-Compiler-API#a-simple-transform-function), but it cannot generate source map
 * TypeScript v1.6+ has [ts.transpile()](https://github.com/Microsoft/TypeScript/wiki/Using-the-Compiler-API#a-simple-transform-function) with source map, but it always ignores type checking
 
+## Known issues
+
+- Windows: `TypeError: Cannot read property 'text' of undefined error.` ([#47](https://github.com/teppeis/typescript-simple/pull/47))
+
 ## Versioning
 
 * typescript-simple v1.x.x uses TypeScript v1.4