Add compilation how-to to README

[nahuakang]

Thanks for writing this binding.

As someone unfamiliar with C and system programming, I had a bit of trouble to get started with using your binding. Would you consider adding some how-to to the README file, something like below? That might hopefully help other newcomers like me to get started faster.

Compile on Unix-like

1. Navigate to https://www.sqlite.org/download.html and download latest amalgamation source version of SQLite.
2. Unzip it in your desired location.
3. In the terminal, run the following commands to compile the static library:

gcc -c sqlite3.c
ar cr sqlite3.a sqlite3.o

4. Move the sqlite3.a static library file to odin-sqlite folder.

Compile on Windows

I assume that you already created C++ Win32 project where you want to include SQLite.

1. Navigate to https://www.sqlite.org/download.html and download latest amalgamation source version of SQLite.
2. Unzip it in your desired location.
3. Run Developer Command Prompt for VS **** to open up a powershell command prompt.
4. Navigate with command prompt to that directory where we extracted our SQLite and run the following:

cl /c /EHsc sqlite3.c
lib sqlite3.obj

5. Move the sqlite3.lib static library file to odin-sqlite folder.
6. On Windows, modify the line in the sqlite3.odin file to:

when ODIN_OS ==  .Windows do foreign import sqlite "sqlite3.lib"