[ci skip] Changes some wording to better foreshadow what is coming up later.
This should prevent some anxiety readers may experience when the doc goes into something different than what it just explained. Also clarifies a statement about priority in engines and application environments

[ci skip] fixes double `the`

[ci skip] more clarifications

[ci skip] changes from tics to quotes
Fix typo in comment
Merge pull request #16029 from cade/fix_typo_in_comment

Fix typo in comment
Merge pull request #15941 from variousred/docrails-changes

[ci skip] Changes some wording to better foreshadow what is coming up later
Use the type object for type casting HStore columns
Do not rely on the column type when quoting infinity
Merge pull request #16034 from sgrif/sg-hstore-type-object

Use the type object for type casting HStore columns
Merge pull request #16036 from sgrif/sg-datetime-infinity

Do not rely on the column type when quoting infinity
Fix guide. sample code syntax error.[ci skip]
Merge pull request #16038 from tbpgr/fix_guide_active_record_validations

Fix guide. sample code syntax error.[ci skip]