a11y: Ensure descriptions on Vega chart examples

packages/webapp/src/components/charts/Vega/specs/area.json

@@ -1,5 +1,6 @@
 {
 	"$schema": "https://vega.github.io/schema/vega/v5.json",
+	"description": "Example Vega area chart using synthetic data.",
 	"autosize": "fit",
 	"data": [
 		{

packages/webapp/src/components/charts/Vega/specs/bar.json

@@ -1,5 +1,6 @@
 {
 	"$schema": "https://vega.github.io/schema/vega/v5.json",
+	"description": "Example Vega bar chart using synthetic data.",
 	"autosize": "fit",
 	"data": [
 		{

packages/webapp/src/components/charts/Vega/specs/donut.json

@@ -1,5 +1,6 @@
 {
 	"$schema": "https://vega.github.io/schema/vega/v5.json",
+	"description": "Example Vega donut chart using synthetic data.",
 	"autosize": "fit",
 	"signals": [
 		{

packages/webapp/src/components/charts/Vega/specs/line.json

@@ -1,5 +1,6 @@
 {
 	"$schema": "https://vega.github.io/schema/vega/v5.json",
+	"description": "Example Vega line chart using synthetic data.",
 	"autosize": "fit",
 	"data": [
 		{

packages/webapp/src/components/charts/Vega/specs/pyramid.json

@@ -1,5 +1,6 @@
 {
 	"$schema": "https://vega.github.io/schema/vega/v5.json",
+	"description": "Example Vega population pyramid chart.",
 	"autosize": "fit",
 	"signals": [
 		{

packages/webapp/src/components/charts/Vega/specs/scatter-plot.json

@@ -1,5 +1,6 @@
 {
 	"$schema": "https://vega.github.io/schema/vega/v5.json",
+	"description": "Example Vega scatter plot chart using car data.",
 	"autosize": "fit",
 	"data": [
 		{

packages/webapp/src/components/charts/Vega/specs/stacked-area.json

@@ -1,5 +1,6 @@
 {
 	"$schema": "https://vega.github.io/schema/vega/v5.json",
+	"description": "Example Vega stacked area chart using synthetic data.",
 	"autosize": "fit",
 	"data": [
 		{

packages/webapp/src/components/charts/Vega/specs/stacked-bar.json

@@ -1,5 +1,6 @@
 {
 	"$schema": "https://vega.github.io/schema/vega/v5.json",
+	"description": "Example Vega stacked bar chart using synthetic data.",
 	"autosize": "fit",
 	"data": [
 		{

packages/webapp/src/components/charts/Vega/specs/sunburst.json

@@ -1,5 +1,6 @@
 {
 	"$schema": "https://vega.github.io/schema/vega/v5.json",
+	"description": "Example Vega sunburst chart using Flare package hierarchy data.",
 	"autosize": "fit",
 	"data": [
 		{