doc: update example url of ICU
The host page of ICU package which is written as http://download.icu-project.org/files/icu4c/58.1/icu4c-58_1-src.tgz in the guide does not seem to available and they move to GitHub's release page for downloads. Refs http://site.icu-project.org/download/67#TOC-ICU4C-Download as an example. As a minor tweak, I also updated the version number of V8_MINIMUM_ICU_VERSION
in the doc to sync with the actual code in deps/v8/src/objects/intl-objects.h
.
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
documentation is changed or added -
commit message follows commit guidelines