swift234

[docs] Fix libicu paths for Android

https://bugs.swift.org/browse/SR-1264 identified a problem in the documentation: the `--android-icu-uc` and `--android-icu-i18n` are documented in `utils/build-script` as taking the path to *the directory that contains* the `libcicuuc.so` and `libicui18n.so` libraries, not the paths to the libraries themselves. Passing the path to the libraries themselves causes a build error.

Fix the path to prevent people from encountering an error when copying the build script invocation in the docs.