Upgrade Guide: Minor fixes for 1.11.

[usmonster]

• Fixes broken markdown link.
• Fixes typo ("then" -> "than").
• Inaccurate reference $.data() replaced with correct .data().
• Parentheses surrounding issue reference moved inside the link.

[jzaefferer]

Looks good to me. Will let someone else take a look as well.

[scottgonzalez]

Thanks.