Updated mediawiki/extensions
Project: mediawiki/extensions/VisualEditor  8a2b55321c67e6173a33c6bb01ad0f06aec9bb63

docs: Minor improvements

CODING.md
* Document the procedure for adding a new javascript class

ve.dm.MWExternalLinkAnnotation.js
ve.dm.MWInternalLinkAnnotation.js
ve.dm.ElementLinearData.js
ve.dm.LinearData.js
* Add whitespace line before preformatted code to fix a
  rendering bug

Change-Id: I54443ea3d4799328655d279f379d4ddc176c50a0