Some cleanup to the intro of "Choosing a Format"

[ajeanmahoney]

No description provided.

[JayDaley]

Apologies for not responding to this sooner. I don't think this is an improvement for the following reasons:

1. It is important that we explain at the outset that we do not provide a specific tool as many people ask that. If we need to explain that no specific tool is dictated then that should be in addition, not a replacement.
2. Also in the first paragraph, I think the starting point should be on markup language familiarity not tool familiarity because
   1. XML is very complex for newcomers to pick up,
   2. Some tools such as the MS Word template are a lot of work to be productive with.
   3. Without some context, it is not possible for someone to choose a tool and the best context we can give is how easy the process is with that combination of markup language and tool.
   4. This is also how the rest of the page flows, if you know XML well then ..., but if not then use Markdown.
3. In the third paragraph, the point here is that our processes are designed around RFCXML and so there may be multiple points where a Markdown to RFCXML conversion is needed so it is better to avoid identifying a specific place. Also "seamlessly" implies that there are some gaps but it is supported at the start and finish, when as we know, support stops fairly early in the process.