feat: Rework Conclusions and Recommendations in H002, H004

Description

Recommendations and Conclusions sections of H002 and H004 reports are fully reworked. The main focus is to make it usable for large databases, where large numbers of unused and redundant indexes need cleanup. Additionally, detailed directions on cleanup tactics are provided.

• the MR description has been reviewed
• this MR contains text changes and they have been reviewed OR there are no texts changes
• this MR contains GUI/CLI changes and they have been reviewed OR there are no GUI/CLI changes
• this MR contains API changes and they have been reviewed OR there are no API changes

Related issue

#484 (closed)

Examples

H002

https://gitlab.com/postgres-ai/postgres-checkup-tests/blob/master/dmius-h002-h004-do-undo/md_reports/1_2019_10_29T06_35_11_+0000/H002.md!

H004

https://gitlab.com/postgres-ai/postgres-checkup-tests/blob/master/dmius-h002-h004-do-undo/md_reports/1_2019_10_29T06_35_11_+0000/H004.md