docs: improve Raman description for vendors
docs: improve Raman description for vendors

Suggested-by: Melin, Stefan M. <f6812e94e093f79362ff400f82f84b6ee153d97d@teliacompany.com>
Change-Id: Ib8a1b66cc28bddc512ac529f9326490b1092be79

Telecominfraproject/gnpy