Add docs

Author: SOHELAHMED7

Makefile

@@ -49,7 +49,7 @@ test: unit test-recursion.json test-recursion2.yaml test-recursion3_index.yaml t
 unit:
 	$(DOCKER_PHP) php $(PHPARGS) $(XPHPARGS) vendor/bin/phpunit --exclude-group gigantic --verbose --colors=always $(TESTCASE)
 
-unit_gigantic: # run test which requires big packages: apis-guru/openapi-directory, nexmo/api-specification
+unit_gigantic: # run test which requires big packages (>778 MB): apis-guru/openapi-directory, nexmo/api-specification
 	$(DOCKER_PHP) php $(PHPARGS) $(XPHPARGS) vendor/bin/phpunit --group gigantic --verbose --colors=always
 
 # test specific JSON files in tests/spec/data/

README.md

@@ -320,6 +320,8 @@ You may use the docker environment for local development:
     docker-compose build
     make IN_DOCKER=1 install
     make IN_DOCKER=1 test
+    make IN_DOCKER=1 unit # run all tests except a big test (below)
+    make IN_DOCKER=1 unit_gigantic # run only a big test
     ...