Merge branch 'jc/conf-var-doc'

Longstanding configuration variable naming rules has been added to
the documentation.

* jc/conf-var-doc:
CodingGuidelines: describe naming rules for configuration variables
config.txt: mark deprecated variables more prominently
config.txt: clarify that add.ignore-errors is deprecated

diff --cc Documentation/CodingGuidelines
Simple merge

diff --cc Documentation/config.txt
index ae6791db128130080915bf127cfa66b850921f43,8a76d1dc2af13f364f03b6c582a4d94e419f33f0..440784cbdd4eaca18e295e382b7568146c0c1e78
--- 1/Documentation/config.txt
--- 2/Documentation/config.txt
+++ b/Documentation/config.txt
@@@ -2341,12 -2269,10 +2340,12 @@@ sendemail.smtpserverport:
  sendemail.smtpserveroption::
  sendemail.smtpuser::
  sendemail.thread::
 +sendemail.transferencoding::
  sendemail.validate::
 +sendemail.xmailer::
        See linkgit:git-send-email[1] for description.
  
- sendemail.signedoffcc::
+ sendemail.signedoffcc (deprecated)::
        Deprecated alias for 'sendemail.signedoffbycc'.
  
  showbranch.default::