added descriptions to showcase examples

hard-coded/showcase/high-dimension-data-subsection-placeholder/config.json

@@ -1,5 +1,6 @@
 {
     "has_thumbnail": false,
     "name": "High Dimension Data",
+    "description": "Data sets with many correlated fields are too big to display all at once. This demo shows how to let the user change the X and Y data, and demonstrates correlated hover info across plots.",
     "relative_url": "high-dimension-data"
 }

hard-coded/showcase/range-slider-subsection-placeholder/config.json

@@ -1,5 +1,6 @@
 {
     "has_thumbnail": false,
     "name": "Range Slider",
+    "description": "Learn to implement a range bar, as an alternate way of zooming in and out on a plot. Use click events to dynamically annotate the plot.",
     "relative_url": "range-slider"
 }

hard-coded/showcase/streaming-data-subsection-placeholder/config.json

@@ -1,5 +1,6 @@
 {
     "has_thumbnail": false,
     "name": "Streaming Data",
+    "description": "Live updating plots can still be zoomed, panned, and autoscaled. Monitor and adjust your equipment or model in real time.",
     "relative_url": "streaming-data"
 }

hard-coded/showcase/style-controls-subsection-placeholder/config.json

@@ -1,5 +1,6 @@
 {
     "has_thumbnail": false,
     "name": "Style Controls",
+    "description": "Update any aspect of a plot’s appearance on the fly with one simple command.",
     "relative_url": "style-controls"
 }