[DOCS] Add JSON to the list of acronyms in the documentation's appendix

The following documentation comment has been logged on the website: Page: https://www.postgresql.org/docs/10/static/acronyms.html Description: Hello all, I propose to add 'JSON' (for JavaScript Object Notation, http://json.org) to the list of acronyms in the documentation's appendix (https://ww

[DOCS] Duplicative index entries in v10/HEAD builds

In 9.6, the HTML doc build's index entry for "data type" looks like data type, Data Types base, The PostgreSQL Type System category, Overview composite, The PostgreSQL Type System constant, Constants of Other Types conversion, Type Conversion enumerated (enum), Enumerated T