Document new variables

doc/ci/variables/README.md

@@ -41,6 +41,9 @@ future GitLab releases.**
 | **CI_COMMIT_REF_SLUG**          | 9.0    | all    | `$CI_COMMIT_REF_NAME` lowercased, shortened to 63 bytes, and with everything except `0-9` and `a-z` replaced with `-`. No leading / trailing `-`. Use in URLs, host names and domain names. |
 | **CI_COMMIT_SHA**               | 9.0    | all    | The commit revision for which project is built |
 | **CI_COMMIT_TAG**               | 9.0    | 0.5    | The commit tag name. Present only when building tags. |
+| **CI_COMMIT_MESSAGE**           | 10.8   | all    | The full commit message. |
+| **CI_COMMIT_TITLE**             | 10.8   | all    | The title of the commit - the full first line of the message |
+| **CI_COMMIT_DESCRIPTION**       | 10.8   | all    | The description of the commit: the message without first line, if the title is shorter than 100 characters; full message in other case. |
 | **CI_CONFIG_PATH**              | 9.4    | 0.5    | The path to CI config file. Defaults to `.gitlab-ci.yml` |
 | **CI_DEBUG_TRACE**              | all    | 1.7    | Whether [debug tracing](#debug-tracing) is enabled |
 | **CI_DISPOSABLE_ENVIRONMENT**   | all    | 10.1   | Marks that the job is executed in a disposable environment (something that is created only for this job and disposed of/destroyed after the execution - all executors except `shell` and `ssh`). If the environment is disposable, it is set to true, otherwise it is not defined at all. |