branded doc: allow to override product name also in doc

...stration_and_usage/basic_administration_and_usage-v1.7.md

...stration_and_usage/basic_administration_and_usage-v1.8.md

...istration_and_usage/testing_and_using_fod_with_freertr.md

doc/api/api-v1.3.md

doc/api/api-v1.7.md

doc/api/api-v1.8.md

doc/configuration/configuration-v1.3.md

doc/configuration/configuration-v1.7.md

doc/configuration/configuration-v1.8.md

doc/index.md

doc/installation/v1.3/debian_wheezy.md

doc/installation/v1.3/generic.md

doc/installation/v1.3/redhat.md

doc/installation/v1.7/centos.md

doc/installation/v1.7/debian_ubuntu.md

doc/installation/v1.7/docker.md

doc/installation/v1.7/docker_extra.md

doc/installation/v1.7/generic.md

doc/installation/v1.8/centos.md

doc/installation/v1.8/debian_ubuntu.md