Add snippet generator link and documentation[JENKINS-65460]

[Queen-esther01]

I added a bit of documentation for the workflow durable task step plugin with examples relating to scripted and declarative pipelines and also referencing the pipeline syntax generator

@MarkEWaite

[MarkEWaite]

@kwhetstone , @aHenryJard , and @StackScribe, would any of you be able to help me with this review. I'm running behind schedule and could really use some help

[jglick]

Also seems to conflict with #154, #156, #157, #158, and #159. Can these all be rolled together into one documentation update?

[MarkEWaite]

Also seems to conflict with #154, #156, #157, #158, and #159. Can these all be rolled together into one documentation update?

Absolutely. Will it be reviewed and merged if I do it?

[jglick]

I will try to review it. Ping me as needed.