Review Standards - Change `r-jira` to `r-explain`

In keeping with the discussions about JIRA, Gitlab, and issue management
(e.g.  https://lab.civicrm.org/infrastructure/ops/issues/817), this change
would revise the "Review Standards".  Instead of specifically requiring
*a JIRA issue* for every PR, it requires *a public explanation* (which can be
provided by JIRA, Gitlab, etc).

Note: This change tries to be the smallest reasonable alteration to the
review criteria that accomodates Gitlab.  However, perhaps we could make it
better -- e.g.  by providing examples of good and bad explanations?

Related: https://github.com/civicrm/civicrm-core/blob/master/.github/PULL_REQUEST_TEMPLATE.md

docs/standards/review.md

@@ -7,7 +7,7 @@ be done, then it can help to post a link to the relevant guideline.  This practi
 write a long, bespoke blurb.
 
 !!! tip "Standard codes"
-    Each standard has a code name (e.g. `r-jira`). These make it easier to reference the standards when chatting with others about PR review.
+    Each standard has a code name (e.g. `r-explain`). These make it easier to reference the standards when chatting with others about PR review.
 
 ## Templates
 
@@ -18,11 +18,15 @@ You may conduct a structured review, checking each standard in turn. Doing this
 
 ## Common standards
 
-### JIRA {:#r-jira}
+### Explanation {:#r-explain}
 
-_Standard code: `r-jira`_
+_Standard code: `r-explain`_
 
-For most bug-fixes and improvements, there needs to be a [JIRA issue](/tools/issue-tracking.md#jira). However, [NFC](/tools/git.md#nfc) and [WIP](/tools/git.md#wip) PRs may not need an issue.
+This change may be inspected by current+future colleagues who (a) want to understand what's improved in the next release and/or (b) need to understand why the system works the way it does. 
+
+Ensure that PR has an adequate explanation. The explanation may be directly in the PR description, or it could be linked in a [JIRA issue](/tools/issue-tracking.md#jira)[Gitlab issue](http://lab.civicrm.org/), or [StackExchange](https://civicrm.stackexchange.com/) thread.
+
+Exception: [NFC](/tools/git.md#nfc) and [WIP](/tools/git.md#wip) PRs may not need a detailed explanation.
 
 ### Test results {:#r-test}
 

docs/standards/review/template-del-1.0.md

-(*CiviCRM Review Template DEL-1.0*)
+(*CiviCRM Review Template DEL-1.1*)
 
 <!-- In each category, choose the option that most applies. Delete the others. Optionally, provide more details or explanation in the "Comments". -->
 
-* JIRA ([`r-jira`](https://docs.civicrm.org/dev/en/latest/standards/review/#r-jira))
+* JIRA ([`r-explain`](https://docs.civicrm.org/dev/en/latest/standards/review/#r-explain))
     * __UNREVIEWED__
-    * __PASS__ : The PR has a JIRA reference. (Or: it does not need one.)
-    * __ISSUE__: Please file a ticket in [JIRA](http://issues.civicrm.org/) and place it in the subject
+    * __PASS__ : The problem+goal have been adequately explained in the PR.
+    * __PASS__ : The problem+goal have been adequately explained with a link (StackExchange, Github, or Gitlab).
+    * __ISSUE__: Please provide a better explanation of the issue being addressed.
+    * __ISSUE__: Please provide a better explanation of how this solution works.
     * __COMMENTS__: <!-- optional -->
 * Test results ([`r-test`](https://docs.civicrm.org/dev/en/latest/standards/review/#r-test))
     * __UNREVIEWED__

docs/standards/review/template-mc-1.0.md

-(*CiviCRM Review Template MC-1.0*)
+(*CiviCRM Review Template MC-1.1*)
 
 <!-- In each category, choose the option that most applies. Optionally, provide more details or explanation in the "Comments". -->
 
-* JIRA ([`r-jira`](https://docs.civicrm.org/dev/en/latest/standards/review/#r-jira))
-    * [ ] __PASS__ : The PR has a JIRA reference. (Or: it does not need one.)
-    * [ ] __ISSUE__: Please file a ticket in [JIRA](http://issues.civicrm.org/) and place it in the subject
+* JIRA ([`r-explain`](https://docs.civicrm.org/dev/en/latest/standards/review/#r-explain))
+    * [ ] __PASS__ : The problem+goal have been adequately explained in the PR.
+    * [ ] __PASS__ : The problem+goal have been adequately explained with a link (StackExchange, Github, or Gitlab).
+    * [ ] __ISSUE__: Please provide a better explanation of the issue being addressed.
+    * [ ] __ISSUE__: Please provide a better explanation of how this solution works.
     * [ ] __COMMENTS__: <!-- optional -->
 * Test results ([`r-test`](https://docs.civicrm.org/dev/en/latest/standards/review/#r-test))
     * [ ] __PASS__: The test results are all-clear.

docs/standards/review/template-word-1.0.md

-(*CiviCRM Review Template WORD-1.0*)
+(*CiviCRM Review Template WORD-1.1*)
 
 <!-- In each category, change the word "Undecided" to "Pass" or "Issue". Add explanatory comments if prompted or desired. -->
 
-* ([`r-jira`](https://docs.civicrm.org/dev/en/latest/standards/review/#r-jira)) __Undecided__
+* ([`r-explain`](https://docs.civicrm.org/dev/en/latest/standards/review/#r-explain)) __Undecided__
 * ([`r-test`](https://docs.civicrm.org/dev/en/latest/standards/review/#r-test)) __Undecided__
 * ([`r-code`](https://docs.civicrm.org/dev/en/latest/standards/review/#r-code)) __Undecided__
 * ([`r-doc`](https://docs.civicrm.org/dev/en/latest/standards/review/#r-doc)) __Undecided__