Add yamllint (#321)

Reviewed-on: https://codeberg.org/Codeberg/pages-server/pulls/321
Reviewed-by: crapStone <codeberg@crapstone.dev>
Co-authored-by: pat-s <patrick.schratz@gmail.com>
Co-committed-by: pat-s <patrick.schratz@gmail.com>

.yamllint.yaml

@@ -0,0 +1,19 @@
+extends: default
+
+rules:
+  comments:
+    require-starting-space: false
+    ignore-shebangs: true
+    min-spaces-from-content: 1
+  braces:
+    min-spaces-inside: 1
+    max-spaces-inside: 1
+  document-start:
+    present: false
+  indentation:
+    spaces: 2
+    indent-sequences: true
+  line-length:
+    max: 256
+  new-lines:
+    type: unix