doc: Improve integrations examples (#3416)

integrations/README.md

+# Integrations tests
+
 Integration tests can be run with make commands for the
 appropriate backends, namely:
 
   make test-pgsql
   make test-sqlite
 
-# Running individual tests
+Make sure to perform a clean build before running tests:
+
+    make clean build
+
+## Run all tests via local drone
+```
+drone exec --local --build.event "pull_request"
+```
+
+## Run sqlite integrations tests
+Start tests 
+```
+make test-sqlite
+```
+
+## Run mysql integrations tests
+Setup a mysql database inside docker
+```
+docker run -e "MYSQL_DATABASE=test" -e "MYSQL_ALLOW_EMPTY_PASSWORD=yes" --rm --name mysql mysql:5.7 #(just ctrl-c to stop db and clean the container) 
+```
+Start tests based on the database container
+```
+TEST_MYSQL_HOST="$(docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' mysql):3306" TEST_MYSQL_DBNAME=test TEST_MYSQL_USERNAME=root TEST_MYSQL_PASSWORD='' make test-mysql
+```
+
+## Run pgsql integrations tests
+Setup a pgsql database inside docker
+```
+docker run -e "POSTGRES_DB=test" --rm --name pgsql postgres:9.5 #(just ctrl-c to stop db and clean the container) 
+```
+Start tests based on the database container
+```
+TEST_PGSQL_HOST=$(docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' pgsql) TEST_PGSQL_DBNAME=test TEST_PGSQL_USERNAME=postgres TEST_PGSQL_PASSWORD=postgres make test-pgsql
+```
+
+## Running individual tests
 
 Example command to run GPG test with sqlite backend:
 
   -test.v -test.run GPG
 ```
 
-Make sure to perform a clean build before running tests:
-
-    make clean build