module search paths

[Brian Tiffin]

Just tried the JSON sample from the home page.  It's not an all 
in listing, so I added an `import std.json;`.  That did not 
include the JSONType enum.  A little more looking around, a more 
complete listing, added

```
import std.array;
import std.conv;
import std.range.primitives;
import std.traits;
```
from the listing in phobos lib docs.

Still no joy. Is there a go to quick and easy way of tracking 
down module members?

```
jsoning.d:40:27: error: undefined identifier ‘JSONType’
    40 |        if (code.type() == JSONType.integer)
       |                           ^
```

With `import std.json` working for the other symbols like 
parseJSON?

`gdc-11 (Ubuntu 11.1.0-1ubuntu1~18.04.1) 11.1.0`

Have good.