[docs] Updates to Readme

[bsieber-mozilla]

Any other spots in the docs need updating @mozilla/jbi-reviewers ?

[leplatrem]

This looks sound.

There are other bits of the README that can be slightly inaccurate like:

• The system sets the see_also field of the Bugzilla bug with the URL to the Jira issue: this is now a possible step instead of a systematic behavior
• some missing comma in the allow_private parameter description
• In the **Parameters** section, the default values are not specified consistently
• Missing new line before ### Available Steps

[bsieber-mozilla]

The system sets the see_also field of the Bugzilla bug with the URL to the Jira issue: this is now a possible step instead of a systematic behavior

@leplatrem if the setting of the see_also is optional, how are we planning to "link" bugs instead of making dupes each time?

It is my understanding that the see_also is the only connection to the downstream link

- some missing comma in the allow_private parameter description
- In the **Parameters** section, the default values are not specified consistently
- Missing new line before ### Available Steps

I'll take a look to update these as well--thanks for the callouts

[bsieber-mozilla]

Merging this in; migrating other concerns to an issue to further discuss