Amend React docs and showcases by colon (:) for Input Form

[mengbingguo]

Description

Having a colon is mandatory in the Fiori Guidelines (SAPUI5 renders that automatically), in the Fundamental React docs it's rather displayed as an additional case and not the default.

I think we should make it Fiori-compliant, showcases need to have colon in input label by default.

Reproduction

SAPUI5:

Fundamental React:

Reference

Fiori Guidelines: https://experience.sap.com/fiori-design-web/form/#guidelines

At the end of the label, the form container automatically inserts a colon (:), which is triggered by the stylesheet. Do not write the colon manually in the label text.

Fundamental React Docs: https://sap.github.io/fundamental-react/iframe.html?id=component-api-forms-formlabel--primary&viewMode=docs#include-colon