Site: Remove contributors name from commit summary

See discussion in dev@ list[1].

[1] https://lists.apache.org/thread.html/r0e198225f7912fa3d6eb910b9c271b2856cf156e87caadca5bf4cd8e%40%3Cdev.calcite.apache.org%3E
diff --git a/site/_docs/howto.md b/site/_docs/howto.md
index 70111c2..11edc39 100644
--- a/site/_docs/howto.md
+++ b/site/_docs/howto.md
@@ -596,9 +596,6 @@
 otherwise it is preferred to do this manually since it saves time and also
 avoids unnecessary notification messages to many people on GitHub.
 
-If the contributor is not a committer, add their name in parentheses at the end
-of the first line of the commit message.
-
 If the merge is performed via command line (not through the GitHub web
 interface), make sure the message contains a line "Close apache/calcite#YYY",
 where YYY is the GitHub pull request identifier.
diff --git a/site/develop/index.md b/site/develop/index.md
index b99bf0e..29770cd 100644
--- a/site/develop/index.md
+++ b/site/develop/index.md
@@ -143,7 +143,7 @@
 the JIRA case number, like this:
 
 {% highlight text %}
-[CALCITE-345] AssertionError in RexToLixTranslator comparing to date literal (FirstName LastName)
+[CALCITE-345] AssertionError in RexToLixTranslator comparing to date literal
 {% endhighlight %}
 
 If your change had multiple commits, use `git rebase -i master` to
@@ -158,6 +158,7 @@
  * The message is often, but not always, the same as the JIRA subject.
 If the JIRA subject is not clear, change it (perhaps move the original
 subject to the description of the JIRA case, if it clarifies).
+ * Leave a single space character after the JIRA id.
  * Start with a capital letter.
  * Do not finish with a period.
  * Use imperative mood ("Add a handler ...") rather than past tense
@@ -168,8 +169,6 @@
  * If you are fixing a bug, it is sufficient to describe the bug
  ("NullPointerException if user is unknown") and people will correctly
  surmise that the purpose of your change is to fix the bug.
- * If you are not a committer, add your name in parentheses at the end
- of the message.
 
 Then push your commit(s) to GitHub, and create a pull request from
 your branch to the calcite master branch. Update the JIRA case