[docs] Add messages in v5 doc to inform people about v6 (#7838)

Signed-off-by: Flavien DELANGLE <flaviendelangle@gmail.com>
Co-authored-by: Lukas <llukas.tyla@gmail.com>

docs/data/date-pickers/date-picker/date-picker.md

@@ -11,6 +11,16 @@ materialDesign: https://material.io/components/date-pickers
 
 <p class="description">The date picker let the user select a date.</p>
 
+:::success
+This component has received several major improvements on the new **v6 beta**:
+
+- [Fields: the new default input for pickers](https://next.mui.com//x/react-date-pickers/fields/).
+- [Improved layout customization](https://next.mui.com//x/react-date-pickers/custom-layout/)
+- [Shortcuts for picking specific dates in a calendar](https://next.mui.com//x/react-date-pickers/shortcuts/)
+
+You can also take a look at [the dedicated blog post](https://mui.com/blog/v6-beta-pickers/) and the [new documentation of the DatePicker](https://next.mui.com/x/react-date-pickers/date-picker/) for more information.
+:::
+
 Date pickers are displayed with:
 
 - Dialogs on mobile

docs/data/date-pickers/date-range-picker/date-range-picker.md

@@ -11,6 +11,17 @@ materialDesign: https://material.io/components/date-pickers
 
 <p class="description">The date range picker let the user select a range of dates.</p>
 
+:::success
+This component has received several major improvements on the new **v6 beta**:
+
+- [Fields: the new default input for pickers](https://next.mui.com//x/react-date-pickers/fields/).
+- [Improved layout customization](https://next.mui.com//x/react-date-pickers/custom-layout/)
+- [Shortcuts for picking specific dates in a calendar](https://next.mui.com//x/react-date-pickers/shortcuts/)
+- [Edit date ranges with drag and drop](https://next.mui.com//x/react-date-pickers/date-range-calendar/)
+
+You can also take a look at [the dedicated blog post](https://mui.com/blog/v6-beta-pickers/) and the [new documentation of the DateRangePicker](https://next.mui.com/x/react-date-pickers/date-range-picker/) for more information.
+:::
+
 ## Basic usage
 
 Note that you can pass almost any prop from [DatePicker](/x/react-date-pickers/date-picker/).

docs/data/date-pickers/date-time-picker/date-time-picker.md

@@ -11,6 +11,16 @@ materialDesign: https://material.io/components/date-pickers
 
 <p class="description">This component combines the date & time pickers.</p>
 
+:::success
+This component has received several major improvements on the new **v6 beta**:
+
+- [Fields: the new default input for pickers](https://next.mui.com//x/react-date-pickers/fields/).
+- [Improved layout customization](https://next.mui.com//x/react-date-pickers/custom-layout/)
+- [Shortcuts for picking specific dates in a calendar](https://next.mui.com//x/react-date-pickers/shortcuts/)
+
+You can also take a look at [the dedicated blog post](https://mui.com/blog/v6-beta-pickers/) and the [new documentation of the DateTimePicker](https://next.mui.com/x/react-date-pickers/date-time-picker/) for more information.
+:::
+
 It allows the user to select both date and time with the same control.
 
 Note that this component is the [DatePicker](/x/react-date-pickers/date-picker/) and [TimePicker](/x/react-date-pickers/time-picker/)

docs/data/date-pickers/time-picker/time-picker.md

@@ -11,6 +11,15 @@ materialDesign: https://material.io/components/time-pickers
 
 <p class="description">Time pickers allow the user to select a single time.</p>
 
+:::success
+This component has received several major improvements on the new **v6 beta**:
+
+- [Fields: the new default input for pickers](https://next.mui.com//x/react-date-pickers/fields/).
+- [Improved layout customization](https://next.mui.com//x/react-date-pickers/custom-layout/)
+
+You can also take a look at [the dedicated blog post](https://mui.com/blog/v6-beta-pickers/) and the [new documentation of the TimePicker](https://next.mui.com/x/react-date-pickers/time-picker/) for more information.
+:::
+
 The selected time is indicated by the filled circle at the end of the clock hand.
 
 ## Basic usage