docs: update blog contribution guidelines (#798)

Co-authored-by: 琚致远 <juzhiyuan@apache.org>
Co-authored-by: Shivam Singh <shivam152002@gmail.com>

website/docs/general/blog-contributing-guide.md

@@ -48,9 +48,11 @@ To add a new blog, please perform the following steps:
 
 #### Blog's header information
 
+##### Single author template
+
 Our blogs start with a header sections containing fields such as `title`, `author`, `authorURL`, `authorImageURL`, `keywords`, `description`, and `tags`.
 
-While `title` and `author` are starightforward, the other fields might be a bit confusing for first-time contributors. Explanations of each field is shown below. Please note that these fields could change over time.
+While `title` and `author` are starightforward, the other fields might be a bit confusing for first-time contributors. Explanation of each field is mentioned below. Please note that these fields could change over time.
 
 ```markdown
 title: "blog's title"
@@ -67,13 +69,37 @@ description: description of this blog
 tags: [tag1]
 ```
 
+##### Co-author template
+
+[Co-author](https://docusaurus.io/docs/next/blog#blog-post-authors) feature is added, since translating and editing articles is also time-consuming, we would like to give credit to translators and technical writers as well.
+
+```markdown
+title: "blog's title"
+authors:
+  - name: "Author's Name"
+    title: "Author's title"
+    url: "Author's GitHub"
+    image_url: "Author's Image URL"
+  - name: "Translator/Technical Writer's name"
+    url: "Translator/Technical Writer's GitHub"
+    image_url: "Translator/Technical Writer's Image URL"
+keywords:
+- keywords 1
+- keywords 2
+- keywords 3
+- keywords 4
+- keywords 5
+description: description of this blog
+tags: [tag1]
+```
+
 ##### title
 
-Required field, the title of the article, the standard expression in the form of `title: "title"`.
+Required field for single author template, the title of the article, the standard expression in the form of `title: "title"`.
 
 ##### author
 
-Required field, the article's author name, the standard form of expression for `author: "author"`.
+Required field for single author template, the article's author name, the standard form of expression for `author: "author"`.
 
 1. Community author: if you are willing to provide your real name, use your real name, if not, use your GitHub account name.
 
@@ -85,7 +111,16 @@ For business users or business cases, you can leave this item blank. Because Git
 
 ##### authorImageURL
 
-The author's GitHub avatar, it is related with `authorURL`. For the same reason described  above, this is an optional field. See below for how to get the avatar.
+The author's GitHub avatar, it is related with `authorURL`. For the same reason described above, this is an optional field. See below for how to get the avatar.
+
+#### authors
+
+The required field for co-author template. When a blog is co-authored by 2 people, please use `authors` instead of `author` to give credits to both authors. `authors` consists of the following fields: `authors.name`, `authors.url`, `authors.title` and `authors.image_url`.
+
+- `authors.name`: authors' names in plain text, for example: `name: "John Doe"`.
+- `authors.title`: author's title in plain text, for example: `title: "Technical Writer"`.
+- `authors.url`: authors' GitHub pages, for example: `url: "https://github.com/yzeng25"`.
+- `authors.image_url`: author's GitHub avatar, for example: `authors.image_url: "https://avatars.githubusercontent.com/u/36651058?v=4"`.
 
 ##### keywords
 
@@ -110,9 +145,9 @@ Required field, tag, which is used to categorize the blog. Each post has and can
 
 We can help authors to use a better category once a pull request is submitted.
 
-#### How to get the authorImageURL
+#### How to get the authorImageURL or authors.image_url
 
-1. Open Chrome or your preffered browser.
+1. Open Chrome or your preferred browser.
 2. Enter the author's GitHub address to access the author's GitHub home page.
 3. Right click on the author's avatar, and click "copy image address".
 4. Paste image address to the authorImageURL field.