Add DOAP file containing machine-readable information for Airflow (ap…

…ache#34091)

The DOAP file is a standard RDF file that describes project's
metadata. The Apache Software Foundation uses DOAP files for
projects to keep project listing information at
https://projects.apache.org/projects.html

After merging this file we can point the ASF index to it and
also add later some automation - for example about releases.

For now adding just basic information should be enough.

doap_airflow.rdf

@@ -0,0 +1,48 @@
+<?xml version="1.0"?>
+<?xml-stylesheet type="text/xsl"?>
+<rdf:RDF xml:lang="en"
+         xmlns="http://usefulinc.com/ns/doap#"
+         xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+         xmlns:asfext="http://projects.apache.org/ns/asfext#"
+         xmlns:foaf="http://xmlns.com/foaf/0.1/">
+<!--
+    Licensed to the Apache Software Foundation (ASF) under one or more
+    contributor license agreements.  See the NOTICE file distributed with
+    this work for additional information regarding copyright ownership.
+    The ASF licenses this file to You under the Apache License, Version 2.0
+    (the "License"); you may not use this file except in compliance with
+    the License.  You may obtain a copy of the License at
+
+         https://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+-->
+  <Project rdf:about="https://airflow.apache.org">
+    <created>2023-09-04</created>
+    <license rdf:resource="https://spdx.org/licenses/Apache-2.0" />
+    <name>Apache Airflow</name>
+    <homepage rdf:resource="https://airflow.apache.org" />
+    <asfext:pmc rdf:resource="https://airflow.apache.org" />
+    <shortdesc>Workflow automation platform</shortdesc>
+    <description>The mission of Apache Airflow is the creation and maintenance of software
+related to workflow automation and scheduling that can be used to author and
+manage data pipelines.
+</description>
+    <bug-database rdf:resource="https://github.com/apache/airflow/issues" />
+    <mailing-list rdf:resource="https://lists.apache.org/list.html?dev@airflow.apache.org" />
+    <download-page rdf:resource="https://airflow.apache.org/docs/apache-airflow/stable/installation/index.html" />
+    <programming-language>Python</programming-language>
+    <programming-language>JavaScript</programming-language>
+    <category rdf:resource="https://projects.apache.org/category/big-data" />
+    <repository>
+      <GitRepository>
+        <location rdf:resource="https://github.com/apache/airflow.git"/>
+        <browse rdf:resource="https://github.com/apache/airflow"/>
+      </GitRepository>
+    </repository>
+  </Project>
+</rdf:RDF>