Need to clean up references in techniques for use of title attribute

[spanchang]

Need to deprecate / delete:
H33: Supplementing link text with the title attribute
H89: Using the title attribute to provide context-sensitive help

Need to modify H28: Providing definitions for abbreviations by using the abbr element.
Instead of demonstrating use of title attribute for abbr, the recommendation should be:

• include visual expansion for the abbreviation right after it on its first use
• include it within a glossary of terms (where one is defined for the content)
  I am not sure of this one (H28)Some screen reader users (perhaps me included) might miss the title on the abbr. Then again, with JAWS for instance, one has to turn on expand abbreviations in settings.

Please read this issue in conjunction with a new failure proposal submitted as a github issue for use of title attribute.
References:

1. https://developer.paciellogroup.com/blog/2013/01/using-the-html-title-attribute-updated/
2. https://html.spec.whatwg.org/multipage/dom.html#the-title-attribute

[patrickhlauke]

See also #3019