Add API reference generation using gi-docgen

docs/meson.build

@@ -0,0 +1,32 @@
+toml_conf = configuration_data()
+toml_conf.set('VERSION', meson.project_version())
+
+docs_dir = get_option('datadir') / 'doc'
+
+casilda_toml = configure_file(
+  input: 'casilda.toml.in',
+  output: 'casilda.toml',
+  configuration: toml_conf,
+  install: true,
+  install_dir: docs_dir / 'casilda',
+)
+
+custom_target('casilda-doc',
+  input: [ casilda_toml, casilda_gir[0] ],
+  output: 'casilda',
+  command: [
+    gidocgen,
+    'generate',
+    ['--quiet', '--no-namespace-dir'],
+    '--add-include-path=@0@'.format(meson.current_source_dir() / '../src'),
+    '--add-include-path=@0@'.format(meson.current_build_dir() / '../src'),
+    '--config=@INPUT0@',
+    '--output-dir=@OUTPUT@',
+    '--content-dir=@0@'.format(meson.current_source_dir()),
+    '@INPUT1@',
+  ],
+  build_by_default: true,
+  install: true,
+  install_dir: docs_dir,
+  install_tag: 'doc',
+)