Edited the Mistake of the PostgreSQL_LIBRARY_DIR comment error.
#6582
- `ICINGA2_WITH_PGSQL`: Determines whether the PostgreSQL IDO module is built; defaults to `ON`
- `PostgreSQL_INCLUDE_DIR`: Top-level directory containing the PostgreSQL include directories
-- `PostgreSQL_LIBRARY_DIR`: Top-level directory containing the PostgreSQL libraries
+- `PostgreSQL_LIBRARY`: File path to PostgreSQL library : libpq.so (or libpq.so.[ver] file)
See [FindMySQL.cmake](third-party/cmake/FindPostgreSQL.cmake) for the implementation.