The page you should be studying is this one:
Trademark policy - Ubuntu
It is a long document but note these selected quotations.
Community advocacy. Ubuntu is built by, and largely for, its
community. We share access to the Trademarks with the entire community
for the purposes of discussion, development and advocacy. We recognise
that most of the open source discussion and development areas are for
non-commercial purposes and will allow the use of the trademarks in
this context, provided:
Please see the provisions listed that must be complied with.
Derived works. The ability to customise Ubuntu to meet your specific
needs is one of the great strengths of free software in general, and
Ubuntu in particular. While we encourage customisation and derivation
of Ubuntu, we must balance that freedom with the integrity of the
Trademarks and the quality which they represent. To help reach that
balance, we have established the following guidelines and definitions.
Please read the guidelines and definitions. It is a section that is too long to be quoted.
Building on Ubuntu or for Ubuntu. If you are producing new software
which is intended for use with or on Ubuntu, you may use the Trademark
in a way which indicates the intent of your product. For example, if
you are developing a system management tool for Ubuntu, acceptable
project titles would be "System Management for Ubuntu" or "Ubuntu
Based Systems Management". We would strongly discourage, and likely
would consider to be problematic, a name such as UbuntuMan, Ubuntu
Management, ManBuntu, etc. Furthermore, you may not use the Trademarks
in a way which implies an endorsement where that doesn't exist, or
which attempts to unfairly or confusingly capitalise on the goodwill
or brand of the project.
Commentary and parody. The Ubuntu trademarks are designed to cover use
of a mark to imply origin or endorsement by the project. When a user
downloads something called Ubuntu, they should know it comes from the
Ubuntu project. This helps Ubuntu build a reputation that will not be
damaged by confusion around what is, and isn't, Ubuntu. Using the
trademarks in your discussion, commentary, criticism or parody, in
ways that unequivocally do not imply endorsement, is permissible.
Anyone is free to write articles, create websites, blog about, or talk
about Ubuntu -- as long as it's clear to everyone -- including people
completely unfamiliar with Ubuntu -- that they are simply referring to
Ubuntu and in no way speaking for Canonical, or the Ubuntu project.
There is a further section called: Restricted use that requires a trademark licence
It is a long section and an individual wishing to make use of Ubuntu in a way that you indicate you wish to use Ubuntu should study that page.
Just noted an important point:
as long as it's clear to everyone -- including people
completely unfamiliar with Ubuntu -- that they are simply referring to
Ubuntu and in no way speaking for Canonical, or the Ubuntu project.
So for the record, I am in no way speaking for Canonical or the Ubuntu project. I am merely directing your attention to information provide by Canonical.