Rectified the correct case (redhat-developer#926)

Author: pabel-rh

modules/customizing-the-appearance/ref-customize-rhdh-default-rhdh.adoc

@@ -88,7 +88,7 @@ app:
               mainSectionBackgroundColor: "#FFF"
               headerBottomBorderColor: "#C7C7C7"
               cardBackgroundColor: "#FFF"
-              sideBarBackgroundColor: "#212427"
+              sidebarBackgroundColor: "#212427"
               cardBorderColor: "#C7C7C7"
               tableTitleColor: "#181818"
               tableSubtitleColor: "#616161"
@@ -180,7 +180,7 @@ app:
               mainSectionBackgroundColor: "#0f1214"
               headerBottomBorderColor: "#A3A3A3"
               cardBackgroundColor: "#292929"
-              sideBarBackgroundColor: "#1b1d21"
+              sidebarBackgroundColor: "#1b1d21"
               cardBorderColor: "#A3A3A3"
               tableTitleColor: "#E0E0E0"
               tableSubtitleColor: "#E0E0E0"