Hipreme's #1 Tip of the day

[Hipreme]

Hey guys, I'm going to start making a tip of the day (although 
I'm pretty sure I won't be able to give every day a tip), but 
those things are really interesting to newcomers to know and may 
be obvious to some of the old schoolers there.

Always public import a type that the user (including you) is 
expected to interact with:

Imagine we have a module A that define a tree

```d
module a;
struct Tree(T){}
```

If you create a module b containing a function that returns a 
tree:

```d
module b;
import a;
Tree!string getDirectoryTree(string entry){return null;}
```
This is virtually unusable! One must `public import a: Tree;`

This will make your API a lot easier to interact with, keep in 
mind to always public import some type that is used from another 
dependency like this, but try to not overdo it.