Storybook: Documenting @grafana/ui components

<!-- Please only use this template for submitting feature requests --> **What would you like to be added**: Tons of documentation. **Why is this needed**: So people understand how to use @grafana/ui. **How** Please see [the guide](https://github.com/grafana/grafana/blob/master/contribute/style-guides/storybook.md#writing-mdx-documentation) on writing MDX docs. ## Missing mdx - [ ] ButtonCascader – details in [#27308](https://github.com/grafana/grafana/issues/27308) - [ ] CallToActionCard - [ ] Chart - [ ] CustomScrollbar - [ ] DataLinks - [ ] FieldConfigs - [ ] Gauge - [ ] Graph - [ ] InfoBox - [ ] InfoTooltip - [ ] JSONFormatter - [ ] Legend - [ ] List - [ ] Logs - [ ] MatchersUI - [ ] OptionsUI - [ ] PanelOptionsGrid - [ ] PanelOptionsGroup - [ ] PieChart - [ ] Portal - [ ] QueryField - [ ] RefreshPicker - [ ] SecretFormField - [ ] Segment - [ ] SetInterval - [ ] SingleStatShared - [ ] StatsPicker - [ ] TabbedContainer - [ ] TableInputCSV - [ ] ThemeColors – see details in [#27184](https://github.com/grafana/grafana/issues/27184) - [ ] ThresholdsEditorNew - [ ] ToggleButtonGroup - [ ] Typeahead - [ ] ValueMappingsEditor - [ ] ValuePicker - [ ] VizRepeater - [ ] transitions - [ ] uPlot ## Missing stories - [ ] Chart - [ ] CustomScrollbar - [ ] DataLinks - [ ] FieldConfigs - [ ] FormLabel - [ ] Gauge - [ ] JSONFormatter - [ ] Logs - [ ] MatchersUI - [ ] OptionsUI - [ ] PanelOptionsGrid - [ ] PanelOptionsGroup - [ ] Portal - [ ] SetInterval - [ ] SingleStatShared - [ ] TabbedContainer - [ ] Typeahead - [ ] VizRepeater - [ ] transitions - [ ] uPlot ## Docs need improving - [ ] Icon – see details in [#27183](https://github.com/grafana/grafana/issues/27183) ## Completed - [x] Alert - [x] AlphaNotice - [x] Badge - [x] BarGauge - [x] BigValue - [x] Button - [x] Cascader - [x] ClickOutsideWrapper - [x] ClipboardButton https://github.com/grafana/grafana/pull/27451 - [x] Collapse - https://github.com/grafana/grafana/pull/27291 - [x] ColorPicker - [x] ConfirmButton https://gi…