Update documentation, with detailed instructions to buid and run Lapis

[c-cesar]

As issue #91 lapis need lua 5.1 (and luarocks 5.1) to work, and can need some symlinks in the filesystem and I can't find this information in the docs. This lack of information in "getting start" manual make the first contact of lapis for some users a 500 error.

[DanielTimLee]

+1 for that.

I've also had problem with loading lapis. [error] 18149#0: *3 lua entry thread aborted: runtime error: content_by_lua(nginx.conf.compiled:22):2: module 'lapis' not found: (Nginx.conf.compiled was totally Default Settings.)

I had to Symlink several folders in ARCH-Linux (4.13.9-1-ARCH)

sudo ln -s /usr/share/lua/5.1 /usr/local/share/lua/5.1
sudo ln -s /usr/lib/lua/5.1 /usr/local/lib/lua/5.1

(ps. lpeg package not found. -Maybe dependency has been broken? ) sudo luarocks install lpeg