Create blog contributions guidelines

Create a new entry for blog posts in the contribution guidelines
section.

content/en/docs/Contribute/blog-guidelines.md

+<!--
+---
+title: "Create a blog post"
+linkTitle: "Create a blog post"
+weight: 6
+description: >
+  Contributions to the Tekton blog are welcome!
+---
+-->
+
+If you have an interesting, fun, or practical idea that you want to share with the
+world, you can write a blog post about it!
+
+Blog posts don't have to follow strict writing rules or styles. They are a good
+place for you to have fun talking about Tekton.
+
+This is how:
+
+## Set up a local version of the website
+
+1.  [Fork][] the [documentation repository][docs-repo].
+
+1.  Clone the repository to your computer:
+
+    ```bash
+    git clone https://github.com/<your-git-username>/website.git
+  
+    ```
+
+1.  [Install Docker Compose][docker-compose], if it's not already installed on
+    your computer. 
+
+1.  Change directory to the repository root and run the website server:
+
+    ```bash
+    cd website
+    docker-compose up
+    ```
+    And wait for the confirmation message to pop up:
+
+    ```
+    ┌─────────────────────────────────────────────────┐
+    │                                                 │
+    │   ◈ Server now ready on http://localhost:8888   │
+    │                                                 │
+    └─────────────────────────────────────────────────┘
+    ```
+
+    Keep the server running while you write your post. Press *Ctrl + C* to stop
+    it.
+
+1.  Open your browser and go to `http://localhost:8888`.
+
+## Draft your blog post
+
+1.  Create a folder under `content/en/blog/<year>/` with a descriptive name.
+    Lower case, use dashes to separate words.
+
+1.  Inside the newly created folder, create a file and add a [front matter][]
+	  with the following format:
+
+    ```yaml
+    ---
+    title: Title
+    likTitle: Title
+    date: <date, for example 2022-10-26>
+    author: "Author name"
+    description: >
+      A heading sentence about your post
+    ---
+    ```
+
+1.	Save the file as `index.md`. As soon as you save it a new blog entry is now
+    visible on your browser.
+
+1.	Below the front matter, write to your heart's content. Every time you save,
+    the server automatically builds the page and shows the changes.
+
+If you need some inspiration, you can find examples on the [website
+repository][blogs-folder].
+
+## Open a PR for review
+
+1.  After you complete your blog post, open a Pull Request and wait for it to
+    be reviewed.
+
+
+1.  Your blog post is now public and we are all excited to read it.
+    Congratulations!
+
+[docs-repo]: https://github.com/tektoncd/website
+[fork]: https://docs.github.com/en/get-started/quickstart/fork-a-repo
+[docker-compose]: https://docs.docker.com/get-docker/
+[front matter]: https://gohugo.io/content-management/front-matter/
+[blogs-folder]: https://github.com/tektoncd/website/tree/main/content/en/blog