Update README with dashboard layout examples

Author: rclement

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Enable extra extensions for Markdown rendering
 
 ### Changed
+- Update README with dashboard layout examples
 - Update dependencies
 
 ## [0.5.3] - 2023-06-05

README.md

@@ -236,6 +236,27 @@ define the `layout` array property as a grid / matrix:
 
 - Each entry represents a row of charts
 - Each column is referring a chart by its property name
+- An empty slot in the grid can be specified using the `.` (_full stop_) placeholder
+
+**WARNINGS**:
+- All rows must specify the same number of columns
+- All charts must be placed somewhere on the custom layout
+
+Here is a simple 2x3 grid example with 4 different charts:
+
+```yaml
+layout:
+  - [chart1, chart2, chart3]
+  - [chart1, chart4, chart4]
+```
+
+Here is a more subtle example involving an empty spot at the end of the second row:
+
+```yaml
+layout:
+  - [chart1, chart2, chart3]
+  - [chart1, chart4, .]
+```
 
 ### Embedding dashboards and charts