docs update.

Author: vitaly-t

README.md

@@ -488,6 +488,7 @@ Example:
 ```js
 // Helper for linking to external query files: 
 function sql(file) {
+    // consider using here: path.join(__dirname, file)
     return new pgp.QueryFile(file, {minify: true});
 }
 
@@ -504,7 +505,7 @@ db.one(sqlFindUser, {id: 123})
         }
     });
 ```
-  
+
 File `findUser.sql`:
 ```sql
 /*

lib/queryFile.js

@@ -87,11 +87,12 @@ var $npm = {
  * // - have your sql provider module as ./sql/index.js
  *
  * var QueryFile = require('pg-promise').QueryFile;
+ * var path = require('path');
  *
  * // Helper for linking to external query files:
  * function sql(file) {
- *     var relativePath = './db/sql/';
- *     return new QueryFile(relativePath + file, {minify: true});
+ *     var fullPath = path.join(__dirname, file); // generating full path;
+ *     return new QueryFile(fullPath, {minify: true});
  * }
  *
  * var sqlProvider = {