Docs: Update documentation on PDF/Email generation with logo (#114005)

Co-authored-by: Isabel Matwawana <76437239+imatwawana@users.noreply.github.com>

docs/sources/visualizations/dashboards/create-reports/report-settings/index.md

@@ -46,7 +46,7 @@ The options in this section control the branding and theming of the report attac
 - **Company logo** - Company logo displayed in the report PDF.
   Configure it by specifying a URL or uploading a file.
   The maximum file size is 16 MB.
-  Defaults to the Grafana logo.
+  If not set, defaults to the Grafana logo. If the specified URL isn't valid, the logo image appears as broken.
 
 - **Theme** - Theme of the PDF attached to the report.
   The selected theme is also applied to the PDFs generated when you click **Preview PDF** during report creation or select the **Export as PDF** option on a dashboard.
@@ -66,7 +66,7 @@ The options in this section control the branding and theming of the report attac
 
 <!-- vale Grafana.WordList = YES -->
 
-- **Company logo** - Company logo displayed in the report email. Configure it by specifying a URL or uploading a file. The maximum file size is 16 MB. Defaults to the Grafana logo.
+- **Company logo** - Company logo displayed in the report email. Configure it by specifying a URL or uploading a file. The maximum file size is 16 MB. If not set, defaults to the Grafana logo. If the specified URL isn't valid, the logo image appears as broken.
 - **Email footer** - Toggle to enable the report email footer. Select **Sent by** or **None**.
 - **Footer link text** - Text of the link in the report email footer. Defaults to `Grafana`.
 - **Footer link URL** - Link of the report email footer.