initial commit for generating the api documentation via phpdocumentor

.gitlab-ci.yml

+stages:
+  - build
+
+pages:
+  image:
+    name: phpdoc/phpdoc:${IMAGE_TAG}
+    entrypoint: [""]
+  stage: build
+  variables:
+    PHPDOC_OUTPUT: "doc/html"
+    IMAGE_TAG: "3.3"
+  script:
+    - git -c http.sslVerify=false clone https://gitlab.studip.de/studip/studip.git --single-branch
+    - cd studip
+    - /opt/phpdoc/bin/phpdoc -t ${PHPDOC_OUTPUT} --config ../phpdoc.xml
+    - mv ${PHPDOC_OUTPUT} ../public
+  artifacts:
+    when: always
+    expose_as: "PHPDoc Build"
+    paths:
+      - public

phpdoc.xml

+<?xml version="1.0" encoding="UTF-8" ?>
+<phpdocumentor configVersion="3"
+               xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+               xmlns="https://www.phpdoc.org"
+>
+    <title>Stud.IP 5.4</title>
+    <paths>
+        <output>docs/html</output>
+        <cache>.caches/phpdoc</cache>
+    </paths>
+
+    <api format="php">
+        <source>
+            <path>lib</path>
+        </source>
+        <ignore hidden="true">
+            <path>vendor/**/*</path>
+            <path>composer/**/*</path>
+            <path>db/**/*</path>
+            <path>locale/**/*</path>
+            <path>templates/**/*</path>
+            <path>tests/**/*</path>
+        </ignore>
+    </api>
+
+</phpdocumentor>