doc(build): minor improvement for build docs #24173

Minor improvement to build documentation, some words are incomplete, correcting simple sentences that take time to understand and lack commas.

Discovered :

• Windows
• Android
• FreeBSD
• NetBSD
• OpenBSD
• OSX
• Unix

After all the build documentation is discovered, I will open the pull request.

I checked the first three replacements and they are wrong English.

Getting started to contribute to Bitcoin Core

Setting up your development environment

New developers are very welcome and needed. There are a lot of open issues of any difficulty waiting to be fixed. However, before you start contributing, familiarize yourself with the Bitcoin Core build system and tests. Refer to the documentation in the repository on how to build Bitcoin Core and how to run the unit and functional tests. Once that is done, you are all set.

If you need more help getting started, please refer to the following resources:

• https://medium.com/@amitiu/onboarding-to-bitcoin-core-7c1a83b20365
• https://jonatack.github.io/articles/how-to-review-pull-requests-in-bitcoin-core

Pick something to work on

If you are looking for useful contributions to help out with, you can

• Search through the good first issues or the ones that are up for grabs. Some of them might no longer be applicable. So if you are interested, but unsure, you might want to leave a comment on the issue first.
• Write tests to improve the coverage. Any kind of test is welcome and coverage information can be obtained from a relatively recent coverage report. If you are unsure, don't hesitate to check back first.
• Help with review and testing. There are easy ones such as the gui and rpc. However, review on any open pull request is welcome. Review will also help you understand the codebase better.
• Help on meta projects related to Bitcoin Core, such as a high-level performance monitor.
• Join us on irc and let us know what you are interested in.