#218 Use of the term "intellectual property" in doc-src/tos

The default Terms of Service (doc-src/tos) use the term "intellectual property", GNU social is part of the GNU project, which [opposes the use of the term "intellectual property"](https://www.gnu.org/philosophy/not-ipr.html), so it should probably not use that. This should probably be changed to either "copyright", "patents", or "trademarks" depending on the context.