Fix bash completion path
The Bazel binary installer said
```
prefix="/usr/local"
bin="%prefix%/bin"
base="%prefix%/lib/bazel"
```
so the bash completion script should be in `/usr/local/lib/bazel/bin` when we run the installer as root.
Closes
@@ -24,7 +24,7 @@ If you installed Bazel:
Example: if you ran the installer with `--user`, this will be
`$HOME/.bazel/bin`. If you ran the installer as root, this will be
- `/usr/local/bazel/bin`.
+ `/usr/local/lib/bazel/bin`.
2. Do one of the following:
* Either copy this file to your completion directory (if you have
one).
