docs: add outdated warnings on style guide pages

Author: Jinjiang

src/style-guide/rules-essential.md

@@ -1,5 +1,9 @@
 # Priority A Rules: Essential {#priority-a-rules-essential}
 
+::: warning Note
+This Vue.js Style Guide is outdated and needs to be reviewed. If you have any questions or suggestions, please [open an issue](https://github.com/vuejs/docs/issues/new).
+:::
+
 These rules help prevent errors, so learn and abide by them at all costs. Exceptions may exist, but should be very rare and only be made by those with expert knowledge of both JavaScript and Vue.
 
 ## Use multi-word component names {#use-multi-word-component-names}

src/style-guide/rules-recommended.md

@@ -1,5 +1,9 @@
 # Priority C Rules: Recommended {#priority-c-rules-recommended}
 
+::: warning Note
+This Vue.js Style Guide is outdated and needs to be reviewed. If you have any questions or suggestions, please [open an issue](https://github.com/vuejs/docs/issues/new).
+:::
+
 Where multiple, equally good options exist, an arbitrary choice can be made to ensure consistency. In these rules, we describe each acceptable option and suggest a default choice. That means you can feel free to make a different choice in your own codebase, as long as you're consistent and have a good reason. Please do have a good reason though! By adapting to the community standard, you will:
 
 1. Train your brain to more easily parse most of the community code you encounter

src/style-guide/rules-strongly-recommended.md

@@ -1,5 +1,9 @@
 # Priority B Rules: Strongly Recommended {#priority-b-rules-strongly-recommended}
 
+::: warning Note
+This Vue.js Style Guide is outdated and needs to be reviewed. If you have any questions or suggestions, please [open an issue](https://github.com/vuejs/docs/issues/new).
+:::
+
 These rules have been found to improve readability and/or developer experience in most projects. Your code will still run if you violate them, but violations should be rare and well-justified.
 
 ## Component files {#component-files}

src/style-guide/rules-use-with-caution.md

@@ -1,5 +1,9 @@
 # Priority D Rules: Use with Caution {#priority-d-rules-use-with-caution}
 
+::: warning Note
+This Vue.js Style Guide is outdated and needs to be reviewed. If you have any questions or suggestions, please [open an issue](https://github.com/vuejs/docs/issues/new).
+:::
+
 Some features of Vue exist to accommodate rare edge cases or smoother migrations from a legacy code base. When overused however, they can make your code more difficult to maintain or even become a source of bugs. These rules shine a light on potentially risky features, describing when and why they should be avoided.
 
 ## Element selectors with `scoped` {#element-selectors-with-scoped}