Update and refine the readme

Author: NickVolynkin

README.md

@@ -4,30 +4,45 @@
 
 ### Test Suite
 
-Bunch of tests, that lay down in the subfolder (recursively) with `suite.ini`
-file. `suite.ini` is basic ini-file, that consists of one section `default`,
+Test suite is a bunch of tests located in a subfolder (recursively) with a `suite.ini`
+file. The `suite.ini` is a basic ini-file with one section `[default]`,
 and a number of fields:
 
-* `core`
-* `description` - Test Suite description
-* `script` - shebang file to start tarantool with
-* disables:
-    * `disabled` - tests that must be skipped
-    * `release_disabled` - tests that must be skipped when Tarantool has been
-      builded with `Release`
-    * `valgrind_disabled` - tests that must be skipped when Valgrind is enabled
-* `lua_libs` - paths for lua files, that should be copied into the folder,
-  where server is started (delimited with the space, e.g. `lua_libs=lua/1.lua
+* `core` — major testing dependency or method
+  Should have one of the following values:
+
+  * `tarantool` — test suite used for functional testing
+  * `app` — TAP-tests, another functional test suite
+  * `unittest` — unit testing test suite
+  * `luatest` — test suite using luatest library
+
+* `description` — test suite description
+* `script` — shebang file to start tarantool with
+
+A number of fields are used to disable (skip) certain tests:
+
+
+* `disabled` — tests that should be skipped
+* `release_disabled` — tests that should be skipped when Tarantool is
+    built with `Release`
+* `valgrind_disabled` — tests that should be skipped when Valgrind is enabled
+
+Other parameters:
+
+* `lua_libs` — paths for lua files, that should be copied into the folder,
+  where server is started. List is delimited by spaces. For example:
+
+  ```ini
+  lua_libs = lua/require_mod.lua lua/serializer_test.lua lua/process_timeout.lua
+  ```
+* 
+* , e.g. `lua_libs=lua/1.lua
   lua/2.lua`)
-* `long_run` - mark tests as long, enabled only with `--long` option (delimited
+* `long_run` — mark tests as long, enabled only with `--long` option (delimited
   with the space, e.g. `long_run=t1.test.lua t2.test.lua`)
-* `config` - test configuration file name
+* `config` — name of a test configuration file
 
-Field `core` must be one of:
 
-* `tarantool` - Test-Suite for Functional Testing
-* `app` - Another functional Test-Suite
-* `unittest` - Unit-Testing Test Suite
 
 ### Test