update readme to show clear example of use_shared_strings for Numbers

1 files changed, 17 insertions, 1 deletions

diff --git a/README.md b/README.md
index ed421766..8aedaec4 100644
--- a/README.md
+++ b/README.md
@@ -209,7 +209,23 @@ related to themes, which axlsx does not implement at this time.
    - border colors do not work
 
 3. Numbers
-   - you must set 'use_shared_strings' to true
+   - you must set 'use_shared_strings' to true. This is most
+     conveniently done just before rendering by calling Package.use_shared_strings = true prior to serialization.
+
+```ruby
+Axlsx::Package.new do |p|
+  p.workbook.add_worksheet(:name => "Pie Chart") do |sheet|
+    sheet.add_row ["Simple Pie Chart"]
+    %w(first second third).each { |label| sheet.add_row [label, rand(24)+1] }
+    sheet.add_chart(Axlsx::Pie3DChart, :start_at => [0,5], :end_at => [10, 20], :title => "example 3: Pie Chart") do |chart|
+      chart.add_series :data => sheet["B2:B4"], :labels => sheet["A2:A4"],  :colors => ['FF0000', '00FF00', '0000FF']
+    end
+  end
+  p.use_shared_strings = true
+  p.serialize('simple.xlsx')
+end
+```
+
    - charts do not render