doc: Rename and update Common-issues.md --> docs/README.md (#2567)

Update the common problems to track with current issues on this repo and shorten the URL to just https://github.com/nodejs/node-gyp/tree/master/docs

Author: cclauss

docs/Common-issues.md

@@ -0,0 +1,11 @@
+## Versions of `node-gyp` that are earlier than v8.x.x
+
+Please look thru your error log for the string `gyp info using node-gyp@` and if that version number is less than the [current release of node-gyp](https://github.com/nodejs/node-gyp/releases) then __please upgrade__ using [these instructions](https://github.com/nodejs/node-gyp/blob/master/docs/Updating-npm-bundled-node-gyp.md) and then try your command again.
+
+## `node-sass` is deprecated
+
+Please be aware that the package [`node-sass` is deprecated](https://github.com/sass/node-sass#node-sass) so you should actively seek alternatives.  Please avoid opening new `node-sass` issues on this repo.  You can try `npm install --global node-sass@latest` but we [cannot help much](https://github.com/nodejs/node-gyp/issues?q=is%3Aissue+label%3A%22Node+Sass+--%3E+Dart+Sass%22+) here.
+
+## Issues finding the installed Visual Studio
+
+In cmd, [`npm config set msvs_version 20xx`](https://github.com/nodejs/node-gyp#on-windows) with ___xx___ matching your locally installed version of Visual Studio.