adds TBC_NAMESPACE as documentation

.gitlab-ci.yml

+# variables in the GitLab CI/CD variables:
+  #   GITLAB_TOKEN to support the semantic-release
+  #   DOCKER_AUTH_CONFIG to support the usage of private docker images as job docker image
+  #   TMPL_RELEASE_ENABLED to enable the semantic-release job
+  #   TBC_NAMESPACE: smartdatalab/public/ci-cd-components
+
 include:
-  - component: git.code.tecnalia.com/smartdatalab/public/ci-cd-components/gitlab-ci/extract@master
+  - component: $CI_SERVER_FQDN/$TBC_NAMESPACE/gitlab-ci/extract@master
     inputs:
       extract-script-job-tags: ["docker"]
-  - component: git.code.tecnalia.com/smartdatalab/public/ci-cd-components/gitlab-ci/validation@master
+  - component: $CI_SERVER_FQDN/$TBC_NAMESPACE/gitlab-ci/validation@master
     inputs:
       check-links-job-tags: ["docker"]
       tbc-check-job-tags: ["docker"]
       tbc-check-image: cicd-docker-dev.artifact.tecnalia.com/tbc-check:master
       gitlab-ci-lint-job-tags: ["docker"]
-  - component: git.code.tecnalia.com/smartdatalab/public/ci-cd-components/kicker/validation@master
+  - component: $CI_SERVER_FQDN/$TBC_NAMESPACE/kicker/validation@master
     inputs:
       kicker-validation-job-tags: ["docker"]
       schema-base-url: "https://git.code.tecnalia.com/api/v4/projects/smartdatalab%2Fpublic%2Fci-cd-components%2Fkicker/repository/files"
       yajsv-image: cicd-docker-dev.artifact.tecnalia.com/yajsv:latest
-  - component: git.code.tecnalia.com/smartdatalab/public/ci-cd-components/bash/gitlab-ci-bash@master
+  - component: $CI_SERVER_FQDN/$TBC_NAMESPACE/bash/gitlab-ci-bash@master
     inputs:
       bash-shellcheck-job-tags: ["docker"]
       shellcheck-files: "*.sh"
-  - component: git.code.tecnalia.com/smartdatalab/public/ci-cd-components/semantic-release/gitlab-ci-semrel@master
+  - component: $CI_SERVER_FQDN/$TBC_NAMESPACE/semantic-release/gitlab-ci-semrel@master
     inputs:
       semantic-release-job-tags: ["docker"]