Rephrase note about "progress bar freezing for some time around 95 percent"

See https://mailman.boum.org/pipermail/tails-testers/2016-February/000430.html

Proposal:

"The progress bar usually freezes for some time around 95 percent while
synchronizing data on disk."

into something like:

"The progress bar usually freezes for some time near the end while
synchronizing data on disk."

or shorter:

"The progress bar usually freezes for some time while synchronizing data
on disk."

Feature Branch: web/11208-not-always-95-percent

Related issues

• Related to #10114

Original created by @sajolida on 11208 (Redmine)