Created a wiki page for performance case studies

Hello,

We, the PostgreSQL Enterprise Consortium in Japan, would like to propose gathering real-world user cases showing the
potentialof PostgreSQL performance in order to promote the use of PostgreSQL.  We've created the initial wiki page: 

Performance Case Study
https://wiki.postgresql.org/wiki/Performance_Case_Study

You can reach here in the PostgreSQL Wiki by going through the links "General articles and guides" -> "Performance Case
Study."

We hope you will find this useful and add more appealing example cases.

[Citation from the page above]
This page showcases real-world user examples that demonstrate the performance of PostgreSQL.  The page is here to
answervague questions from users considering adoption of PostgreSQL, such as "What performance can PostgreSQL offer?",
"Whatsize of database can PostgreSQL handle?", and "Is PostgreSQL used in business critical systems (in a particular
industry)?" This page was created by PostgreSQL Enterprise Consortium (PGECons) [1], a Japanese organization founded to
promoteuse of PostgreSQL in enterprises.  Feel free to add entries. 


[1]
https://www.pgecons.org/en/about/


Regards
Takayuki Tsunakawa