docs: update stale links to GitLab docs (anchors)

README.md

@@ -6,7 +6,7 @@ or [Kustomize](https://kubernetes.io/docs/tasks/manage-kubernetes-objects/kustom
 
 ## Usage
 
-This template can be used both as a [CI/CD component](https://docs.gitlab.com/ee/ci/components/#use-a-component-in-a-cicd-configuration) 
+This template can be used both as a [CI/CD component](https://docs.gitlab.com/ee/ci/components/#use-a-component) 
 or using the legacy [`include:project`](https://docs.gitlab.com/ee/ci/yaml/index.html#includeproject) syntax.
 
 ### Use as a CI/CD component
@@ -279,7 +279,7 @@ by using available environment variables:
     * `${k8s_namespace}`: the Kubernetes namespace currently used for deployment/cleanup
     * `${hostname}`: the environment hostname, extracted from the current environment url (after late variable expansion - see below)
 2. any [GitLab CI variable](https://docs.gitlab.com/ee/ci/variables/predefined_variables.html)
-3. any [custom variable](https://docs.gitlab.com/ee/ci/variables/#add-a-cicd-variable-to-a-project)
+3. any [custom variable](https://docs.gitlab.com/ee/ci/variables/#for-a-project)
     (ex: `${SECRET_TOKEN}` that you have set in your project CI/CD variables)
 
 While your scripts may simply use any of those variables, your Kubernetes and Kustomize resources can use **variable substitution**
@@ -323,7 +323,7 @@ data:
 The K8S template supports two ways of providing your environments url:
 
 * a **static way**: when the environments url can be determined in advance, probably because you're exposing your routes through a DNS you manage,
-* a [**dynamic way**](https://docs.gitlab.com/ee/ci/environments/#set-dynamic-environment-urls-after-a-job-finishes): when the url cannot be known before the
+* a [**dynamic way**](https://docs.gitlab.com/ee/ci/environments/#set-a-dynamic-environment-url): when the url cannot be known before the
   deployment job is executed.
 
 The **static way** can be implemented simply by setting the appropriate configuration variable(s) depending on the environment (see environments configuration chapters):
@@ -368,7 +368,7 @@ You may also add and propagate your own custom variables, by pushing them to the
 
 Here are some advices about your **secrets** (variables marked with a :lock:):
 
-1. Manage them as [project or group CI/CD variables](https://docs.gitlab.com/ee/ci/variables/#add-a-cicd-variable-to-a-project):
+1. Manage them as [project or group CI/CD variables](https://docs.gitlab.com/ee/ci/variables/#for-a-project):
     * [**masked**](https://docs.gitlab.com/ee/ci/variables/#mask-a-cicd-variable) to prevent them from being inadvertently
       displayed in your job logs,
     * [**protected**](https://docs.gitlab.com/ee/ci/variables/#protected-cicd-variables) if you want to secure some secrets