[INTERNAL] docs/developing.md: enhance SDK build description for restricted libraries build
[INTERNAL] docs/developing.md: enhance SDK build description for restricted libraries build

Change-Id: Id5c1c7fa8ba0b4a7f642bf0f4ae8c675c42ec90b

SAP/openui5,SAP/openui5,SAP/openui5,SAP/openui5