Remove personal pronouns

[Samyoul]

Resolves #115

Why make the change?

Technical documents should be written in formal unambiguous language, much of the specifications use a mixture of language modes.

What has changed

• Removed use of personal pronouns
• Removed inappropriate use of passive voice
• Removed ambiguous subjects (mostly a consequence of removing passive voice)

[Samyoul]

For details on the changes see the addition to the README

[Samyoul]

Hey @decanus , I've done some tidying up, and I've addressed the changes you've suggested. Would you mind giving this PR another look over?

Note I've addressed something that Oskar asked me to do https://github.com/status-im/specs/pull/132#discussion_r433167487, which introduces a new STYLE-GUIDELINE.md for all things related to how writing should be done.

[decanus]

@Samyoul I'll have another look tomorrow.