This is very mundane -- how to install (and run bazel..).

For the life of me I can't find any installation instructions nor by thrashing around can I figure out the right bazel invocation.

I'm guessing the instructions would be something like:

1. install bazel
2. git clone https://github.com/google/riegeli.git
3. cd riegeli
4. ./configure
5. bazel build ???

I was able to get `bazel build //riegeli/base:status` to work, but `bazel build //riegeli/...` is unhappy:
`ERROR: /Users/dave/Projects/riegeli/riegeli/tensorflow/io/BUILD:27:11: no such package 'third_party/tensorflow/core/platform': \
BUILD file not found in any of the following directories. Add a BUILD file to a directory to mark it as a package.
- /Users/dave/Projects/riegeli/third_party/tensorflow/core/platform and referenced by '//riegeli/tensorflow/io:file_writer'`

I'm on a Macbook Air, the M1, and its tensorflow is a bit funky, which may be another issue
as I had to fix the output of ./configure since when you import tensorflow you get some
debug output:
```
python -c "import tensorflow"
Init Plugin
Init Graph Optimizer
Init Kernel
```

My goal is to get a c++ and python library built.

Basic info:
uname -a: Darwin daves-air.lan 20.6.0 Darwin Kernel Version 20.6.0: Wed Jun 23 00:26:27 PDT 2021; root:xnu-7195.141.2~5/RELEASE_ARM64_T81\
01 arm64

Python 3.9.4

TF: 2.5.0

thx,
Dave