doc(wiki): if ouns that the -h did not help. I founs on github that t…

…here was support for visual studio 2015, while i couldn't install node-red beacuse it kept telling me the key 2015 was missing. looking in he gyp python code i found the local file was bot up t dat with the github repo. updating took several efforts before i tried to drop the -g option.

Updating-npm's-bundled-node-gyp.md

@@ -41,4 +41,6 @@ Now you can finally run:
 
 ``` bash
 $ npm install -g node-gyp@latest
-```
+```
+
+note: i found that the -g on windows is not correct. It gets installed in C:\Users\<name>\AppData\Roaming\npm\node_modules\gyp which is not the directory where node is installed C:\Program Files (x86)\nodejs\node_modules\npm\node_modules\node-gyp\...