Update documentation

Author: lowlighter

source/plugins/core/README.md

@@ -239,6 +239,21 @@ It could then be processed for other usages.
     config_output: png
 ```
 
+### 🖨️ Convert output to PDF
+
+It is possible to convert output to PDF when using a markdown template by setting `config_output` to `markdown-pdf`.
+
+#### ℹ️ Examples workflows
+
+```yaml
+- uses: lowlighter/metrics@latest
+  with:
+    # ... other options
+    markdown: template.md
+    markdown_cache: .cache
+    config_output: markdown-pdf
+```
+
 ### 🐳 Faster execution with prebuilt docker images
 
 If you're using the official release `lowlighter/metrics` as a GitHub Action (either a specific version, `@latest` or `@master`), it'll pull a prebuilt docker container image from [GitHub Container Registry](https://github.com/users/lowlighter/packages/container/package/metrics) which contains already installed dependencies which will cut execution time from ~5 minutes to ~1 minute.

source/templates/markdown/README.md

@@ -25,12 +25,25 @@ For convenience, several useful properties are aliased in [/source/templates/mar
 #### ℹ️ Examples workflows
 
 ```yaml
+# Markdown output
 - uses: lowlighter/metrics@latest
   with:
     # ... other options
     template: markdown
-    filename: README.md      # Output file
-    markdown: TEMPLATE.md    # Template file
-    markdown_cache: .cache   # Cache folder
-    config_output: markdown  # Output as markdown file
+    filename: README.md         # Output file
+    markdown: TEMPLATE.md       # Template file
+    markdown_cache: .cache      # Cache folder
+    config_output: markdown     # Output as markdown file
+```
+
+```yaml
+# PDF output
+- uses: lowlighter/metrics@latest
+  with:
+    # ... other options
+    template: markdown
+    filename: render.pdf        # Output file
+    markdown: TEMPLATE.md       # Template file
+    markdown_cache: .cache      # Cache folder
+    config_output: markdown-pdf # Output as pdf file
 ```

source/templates/markdown/example.md

@@ -50,7 +50,7 @@ ___
 
 To include SVGs metrics images without creating additional jobs, use the `embed` function:
 
-<%- await embed("example-isocalendar", {isocalendar:true, isocalendar_duration:"full-year"}) %>
+<%- await embed(`example-isocalendar`, {isocalendar:true, isocalendar_duration:"full-year"}) %>
 
 It takes two arguments:
 - An unique identifier which will be used as filename withing `markdown_cache` folder

source/templates/markdown/example.pdf.md

@@ -0,0 +1,13 @@
+# 📒 Markdown template example (pdf)
+
+When using **markdown template**, it is possible to export output as PDF.
+
+See [rendering of this file here](https://github.com/lowlighter/lowlighter/blob/master/metrics.markdown.pdf.md) and [original template source here](https://github.com/lowlighter/metrics/blob/master/source/templates/markdown/example.pdf.md).
+
+## 🧩 Plugins
+
+You can customize your template with both markdown plugins and SVG plugins like below:
+
+<%- await include(`partials/rss.ejs`) %>
+
+<%- await embed(`test-isocalendar`, {isocalendar:true}) %>