feat: migrate backend to cosmiconfig

configuration/backend-config/about-page.xsd

@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">
+  <xs:element name="page">
+    <xs:complexType>
+      <xs:complexContent>
+        <xs:extension base="contents">
+          <xs:attribute name="href" type="xs:string" use="required"/>
+          <xs:attribute name="lang" type="xs:language"/>
+        </xs:extension>
+      </xs:complexContent>
+    </xs:complexType>
+  </xs:element>
+
+  <xs:complexType name="contents">
+    <xs:sequence>
+      <xs:choice minOccurs="0" maxOccurs="unbounded">
+        <xs:element name="section" type="section"/>
+        <xs:element name="link" type="link"/>
+        <xs:element name="markdown">
+          <xs:complexType>
+            <xs:simpleContent>
+              <xs:extension base="xs:string"/>
+            </xs:simpleContent>
+          </xs:complexType>
+        </xs:element>
+        <xs:element name="rows" type="table"/>
+      </xs:choice>
+    </xs:sequence>
+  </xs:complexType>
+
+  <xs:complexType name="table">
+    <xs:sequence>
+      <xs:element name="columns" type="contents" maxOccurs="unbounded" minOccurs="0"/>
+    </xs:sequence>
+  </xs:complexType>
+
+  <xs:complexType name="section">
+    <xs:complexContent>
+      <xs:extension base="contents">
+        <xs:attribute name="title" type="xs:string" use="required"/>
+      </xs:extension>
+    </xs:complexContent>
+  </xs:complexType>
+
+  <xs:complexType name="link">
+    <xs:complexContent>
+      <xs:extension base="xs:normalizedString">
+        <xs:attribute name="icon" type="xs:string" use="required"/>
+        <xs:attribute name="href" type="xs:string" use="required"/>
+      </xs:extension>
+    </xs:complexContent>
+  </xs:complexType>
+</xs:schema>