Microsoft today released a new Office Insider Preview Build 14002.20000 for Windows users registered in the Beta Channel. The new Insider Preview build brings new features for Excel and Word. You can read the full official changelog below.
Changelog
Excel
Accessibility ribbon
Find all of the tools you need to create accessible content in one place – the Accessibility ribbon!
Word
Proofing for selected text within the Document
With these changes you can now review spelling, grammar and other intelligent writing suggestions for just the selected text. Additionally you can also review suggestions for the whole document.
To update to the latest Microsoft Office Insider Preview Build, open any Office program and go to File> Account> Update Options> Update Now.