Document space necessary to complete installing bazel

[cfilleke]

Hi. I'm building bazel using this script on a KVM guest on Z15 -- the default non-volatile storage size if 5 GB, which results in: ```cheryl@ubu22:~$ [119926.884216] systemd-journald[7151]: Failed to create new system journal: No space left on device
[149980.893973] systemd-journald[7151]: Failed to create new system journal: No space left on device

Will need more, but how much?  An estimate would help.  Thanks!

[aborkar-ibm]

Hello, you will need approximately 35 GB to build bazel.