Making it clearer what column_width does (#5996)

Added more words to make it clearer what it does, and how to use a value to get the number of entities you want in a row

source/_lovelace/glance.markdown

@@ -42,7 +42,7 @@ show_state:
   default: "true"
 column_width:
   required: false
-  description: "Column width as CSS length like `100px` or `calc(100% / 7)`."
+  description: "Column width as CSS length like `100px` or `calc(100% / 7)`. This controls how many entities appear in a row - at the default 20% you have 5 entities in a row. Use `calc(100% / 7)` for 7 entities in a row, and so on."
   type: string
   default: 20%
 {% endconfiguration %}