Update doc in SUPPORT.md for disabled-strategies

[NobodyXu]

For #1828 and #1721

[ilyagr]

Thank you very much for implementing this! This PR looks good to me as well.

Is there a plan to have an option like --force-enable-manifest-disabled-strategies or --force-enable-maintainer-unsupported-strategies?

For example, with #1721, if QuickInstall happens to make a binary available for an architecture the maintainer doesn't support, or if QuickInstall binary happens to not have a bug that the official binary does, I'd like the user to be able to use it. I'd just like them to be very aware that they are using an unsupported binary.

[passcod]

CLI options override manifest options already, they assume the user knows what they're doing.

[ilyagr]

Sounds good, thanks!

This might be worth mentioning in this PR. You could add a sentence: "The user can override this by explicitly specifying --strategies on the command line."

[ilyagr]

By the way, this means that --disable-strategies A is no longer equivalent to --strategies B,C. Perhaps this means that --disable-strategies should get its own environment variable config to make the workaround from nabijaczleweli/cargo-update#264 correct again. I might also leave a note there (Update: perhaps after this discussion is done).