Add a field for preferred pronouns

[stp-ip]

Is this a BUG REPORT or FEATURE REQUEST?:
feature

Copied from jsonresume/resume-schema#324

I would like to be able to put my preferred pronouns on my resume. For most users, this will be a bare string (e.g. they/them/theirs), but it should also be possible to add more complex data to it, such as:

pronoun.is link (e.g. http://my.pronoun.is/they)
an array of pronouns to which the theme can apply special formatting
    example: ["they", "them", "theirs"] becomes "they / them / theirs" or "they • them • theirs" depending on the theme

For inspiration, this article discusses how Asana implemented preferred pronouns in profile settings.