[Docs][Android] Fix minimal Android API level

[CmST0us]

When compile swift using NDK, I meet this problem.

/home/eki/Project/swift-project/swift/stdlib/public/runtime/CrashHandlerLinux.cpp:665:12: error: use of undeclared identifier 'process_vm_readv'
    return process_vm_readv(memserver_pid, &local, 1, &remote, 1, 0);
           ^
1 error generated.

I found that this function should use android api level greater than 23

#if __ANDROID_API__ >= 23
ssize_t process_vm_readv(pid_t __pid, const struct iovec* __local_iov, unsigned long __local_iov_count, const struct iovec* __remote_iov, unsigned long __remote_iov_count, unsigned long __flags) __INTRODUCED_IN(23);

[CmST0us]

relate #63708

[finagolfin]

Thanks, I noticed this last week and notified the guy who runs the community Android CI, let's see what he says.

[CmST0us]

@swift-ci Please smoke test

[CmST0us]

Thanks, I noticed this last week and notified the guy who runs the community Android CI, let's see what he says.

got😀, I modify the api level to 23 in build-preset.ini, pls review?

[finagolfin]

I'm not sure what he'll say, let's see.

[finagolfin]

I fixed this in #67478 instead, should keep working with API 21 now. Try it out and close this if it works for you.

[CmST0us]

It works, thanks!