unify YAML variables used accross template by documenting them.

[cderv]

Currently, I don't think all the templates use the same Pandoc variable name for a same purposed variable.

Example:

• acs template

title:
  - short: short title
  - formatted: full title

whereas common pandoc is to use

title: full title
shorttitle: short title

This thread is to compile the used one and decide which to keep

List of common variables that can be uses in a template

• title: Title of the article
• shorttitle: A short title for the article
  • runtitle: used in some format as title in \runtitle but this is quite the same
• author: Field for author informations (see also templates interoperability #324 for author specific uniformisation)
• keywords: Keyword
• shortauthors

[mingsu]

institute: institute(s) of each author
journalname: journal name
corresponding author(s): including author name name and address.

[gregmacfarlane]

runninghead: what gets printed at the top of non-title pages. Wikipedia suggests "running head" over "running header" or "running title"