Add please to README.rst some description

[D-Y-V]

Centos8 build:
a) build process is not recommended in the source tree!!!
b) As we are have 64bit system, libdir must be lib64.

In source root dir do:
$ mkdir binout
$ cd binout
$ cmake -DCMAKE_INSTALL_LIBDIR=lib64 -DCMAKE_BUILD_TYPE=Release ..
$ make
as root:

make install

AND
create in /etc/ld.so.conf.d/ file tarantool-c.conf with content:

 cat  /etc/ld.so.conf.d/tarantool-c.conf 
/usr/local/lib64/

After this, as root execute # ldconfig