[whitepaper][1.5.1][1.5.2]: Comments to the brief history of telcos

I think 1.5.1 and 1.5.2 should be merged in to one chapter. This would solve the two following problems 1) 1.5.1 tells nothing about the history of virtualisation in telcos and 2) 1.5.2 tells nothing about SDN :)

Review whitepaper chapters 1.5.1 and 1.5.2 first. Merge them into one chapter, ensuring the result covers both the history of virtualisation in telcos and SDN; done means the two stated omissions are addressed.

Written by the indexing model from the issue text.