fix(v2): less strict blog/docs uri frontmatter validation (#5032)

packages/docusaurus-utils-validation/src/validationSchemas.ts

@@ -25,8 +25,11 @@ export const RehypePluginsSchema = MarkdownPluginsSchema;
 
 export const AdmonitionsSchema = Joi.object().default({});
 
+// TODO how can we make this emit a custom error message :'(
+//  Joi is such a pain, good luck to annoying trying to improve this
 export const URISchema = Joi.alternatives(
   Joi.string().uri({allowRelative: true}),
+  // This custom validation logic is required notably because Joi does not accept paths like /a/b/c ...
   Joi.custom((val, helpers) => {
     try {
       const url = new URL(val);