Update Boost example

[ScottBailey]

Boost is a great library and it's important to many projects. This PR is written to show an example of escaping input in the OPTIONS argument of CPMAddPackage() and converts from git clone to acquiring the source release archive and testing against a hash.

While a git clone of a github repo often makes sense, even a shallow copy of Boost is time consuming due to the many submodules involved. For my 50mbit connection, it takes almost 3 minutes to clone the repo. Using the github releasse cuts the time to 33 seconds.

This is also the only example of getting the tar of a release from github which, I think, should be the most common approach as it requires the least bandwidth.

I believe this may close #501

Tested in Debian GNU/Linux and Windows 11.

Added information on locating GitHub repository's source archives and determining SHA256 hash values.

[TheLartians]

This is great, thanks for updating the example to show how to use releases!

Would it make sense to also update the boost example in the readme and explaining the advantage of using a release directly for large projects there?

[ScottBailey]

Would it make sense to also update the boost example in the readme and explaining the advantage of using a release directly for large projects there?

It would make a TON of sense to do that. I had forgotten the example was even in the readme. I'll update that in the next couple days and and ask for a rereview.

[TheLartians]

I'll update that in the next couple days and and ask for a rereview.

@ScottBailey any ETA on this? Otherwise we can also go ahead with merging the examples now and update the Readme in a future PR.

[ScottBailey]

I'll update that in the next couple days and and ask for a rereview.

@ScottBailey any ETA on this? Otherwise we can also go ahead with merging the examples now and update the Readme in a future PR.

Let's hold off until Friday COB. I am hoping to have some "free" time then. I made a number of edits but then got pulled away for my paying gig.

[TheLartians]

Thanks for the elaborate readme additions! I wasn't aware GitHub as archive support for any commits. Perhaps this should be the default way for CPM to download repositories using the shorthand syntax - but that can be discussed in the future.