[docs] how to set fixed size of full diagram (#173)

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Co-authored-by: Mc-Zen <52877387+Mc-Zen@users.noreply.github.com>

Author: Rahix

src/model/diagram.typ

@@ -41,21 +41,25 @@
 
   /// The width of the diagram. This can be one of the following:
   /// - A `length`, defining just the width of the data area,
-  ///   excluding axes, labels, title etc.
+  ///   excluding axes, labels, title, etc. To set a `length` including 
+  ///   everything, use `0% + length`, see the next option. 
   /// - A `ratio` or `relative` where the ratio part is relative to the width 
-  ///   of the parent that the diagram is placed in. This is not allowed if the
-  ///   parent has an unbounded width, e.g., a page with `width: auto`.  
+  ///   of the parent that the diagram is placed in. This includes axes, labels, 
+  ///   title, etc. This is not allowed if the parent has an unbounded width, 
+  ///   e.g., a page with `width: auto`.  
   /// - Or `auto` in which case the width is computed automatically based on 
   ///   @diagram.aspect-ratio. 
   /// -> length | relative | auto
   width: 6cm,
 
   /// The height of the diagram. This can be one of the following:
   /// - A `length`, defining just the height of the data area,
-  ///   excluding axes, labels, title etc.
+  ///   excluding axes, labels, title, etc. To set a `length` including 
+  ///   everything, use `0% + length`, see the next option. 
   /// - A `ratio` or `relative` where the ratio part is relative to the height 
-  ///   of the parent that the diagram is placed in. This is not allowed if the
-  ///   parent has an unbounded height, e.g., a page with `height: auto`.  
+  ///   of the parent that the diagram is placed in. This includes axes, labels, 
+  ///   title, etc. This is not allowed if the parent has an unbounded height, 
+  ///   e.g., a page with `height: auto`.  
   /// - Or `auto` in which case the height is computed automatically based on 
   ///   @diagram.aspect-ratio. 
   /// -> length | relative | auto