[v9.5.x] Docs: update heatmap panel options (#71096)

Docs: update heatmap panel options (#71058)

Added some heatmap panel configuration options which were missing from the docs

(cherry picked from commit bdf60d69de)

Co-authored-by: prenzlern <88067634+prenzlern@users.noreply.github.com>

docs/sources/panels-visualizations/visualizations/heatmap/index.md

@@ -38,6 +38,7 @@ Select one of the following Y-axis value scales:
 - **linear -** Linear scale.
 - **log (base 2) -** Logarithmic scale with base 2.
 - **log (base 10) -** Logarithmic scale with base 10.
+- **symlog -** Symlog scale.
 
 ## Y Axes
 
@@ -61,6 +62,14 @@ This setting determines decimal configuration.
 
 This setting configures the axis range.
 
+### Axis width
+
+This setting configures the width for the axis.
+
+### Axis value
+
+This setting configures the axis value.
+
 ### Reverse
 
 When selected, the axis appears in reverse order.