Create documentation for the 1.x branch

Due to lack of documentation, I ended up writing https://www.drupal.org/project/oai_pmh_harvester → without depending on this module.

Something that was useful for me, as a developer who was not a subject-matter expert on bibliographic displays, was to define a glossary of terms related to bibliographic data and to Bibcite's implementation, specifically. Here's a short starter that could be added to this module's documentation (feel free to edit!):

• Citation format: A standardized display of reference information following specific style guidelines. The most common citation formats are Modern Language Association (MLA), American Psychological Association (APA), and Chicago Style.
• Citation Style Language (CSL): An XML file format that describes the schema for existing citation formats like MLA, APA, and Chicago style.
• Individual citation: information about a reference rendered in a standardized citation format (APA, MLA, Chicago Style)
• Bibcite reference: A fieldable Drupal entity type that stores data about citations.
• Bibcite contributor: A fieldable Drupal entity type that stores data about citation authors. This is exposed as an entity reference field on Bibcite references.
• Bibcite keyword: A Drupal entity that functions like a taxonomy tag vocabulary for Bibcite references. This is exposed as an entity reference field on Bibcite references.
• Individual reference page: A dedicated page that lists information about a Bibcite reference, including author information, abstract, and other details. This page does not display this information in one of the citation formats.
• Individual contributor page: A dedicated page that lists Bibcite contributor entity information, as well as a list of all reference entities for which that contributor is named. These entries are displayed in the site's selected citation format.
• Reference listing page: A page that lists all Bibcite references on the site, rendered in the site's selected citation format.
• Import/export format: An API for importing and exporting reference materials. These include BibTeX, Endnote, and RIS, each of which have different rules for processing reference material and for how that data should be formatted. These can be considered analogous to data formats like JSON, YML, and PHP arrays, which have different syntax for storing collections of machine-readable data.