docs: Readme navigation fix for roadmap link

[twosdai]

Fixes the roadmap navigation link inside of the readme to properly point to the roadmap of the SBT readme rather than the CDK.

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[twosdai]

Hey I saw that the readme for the current release incorrectly points to the CDK's roadmap, I created a quick PR in order to fix it. I was confused while reading through the readme about the SBT's roadmap and it seemed CDK specific only to realize that the readme was pointing to the wrong location.

I noticed that you have a naming convention for PR's, I saw that within the link: https://www.conventionalcommits.org/en/v1.0.0/
the title docs is used which I think fits for this, I could also see it as a fix. Let me know if you need me to change anything.

@tobuck-aws I saw that you commited to the repo already, I am not sure if you are the right person to ping regarding getting this reviewed and merged.

[tobuck-aws]

@twosdai, thanks, we appreciate the contribution! We are using conventional commits, but as you mentioned, docs: is acceptable. I think I missed some configuration on our side. I'll get that fixed before I merge this.