Remove the duplicated settings_page row in the table and fix the link to the DAO information on pseudoconstants (#825)

Add note about empty and propertyBag pre 5.28

* Remove suggestion that you *must* use the new parameters 

The docs were incorrectly stating that *only* the new properties are available - as can be demonstrated in this tested code in core - https://github.com/civicrm/civicrm-core/pull/17585/files#diff-925c5486a3ef170b6613caf3da110a18R627 - the legacy params still work and while we recommend change no action is required

* Update to reflect discussion 

I also added clarity on the doCancelRecurring after it was unclear to @KarinG in chat

Add `settings_pages` to main spec

Add note in about deprecation of CRM_Core_Error::fatal

updated the file system documentation link

Document how to implement cancel recur for payment processors

Update hook_civicrm_alterLogTables - Fix unclear statement regarding …

Update civix.md

Removed $ from bash commond, "$" makes problem while copying the command.

Added path of the extension directory, removed some typo and Resolved the issue(#803).

Removed a small typo.

Resolved the issue `Documentation repos are not listed at docs/documentation/index.md #803` (https://github.com/civicrm/civicrm-dev-docs/issues/803).

Added path of the extension directory and removed some typo.

Improve examples of hook_civicrm_alterExternUrl

Update to reflect https://github.com/civicrm/civicrm-core/pull/16903