Link directly to build requirements from threat D

In the "How SLSA could have helped" column of the row describing threat D
"Compromise build platform" instead of linking to the generic requirements
document, link directly to the build requirements section.

README.md

@@ -66,7 +66,7 @@ example:
 | A | Submit bad code to the source repository | [Linux hypocrite commits]: Researcher attempted to intentionally introduce vulnerabilities into the Linux kernel via patches on the mailing list. | Two-person review caught most, but not all, of the vulnerabilities.
 | B | Compromise source control platform | [PHP]: Attacker compromised PHP's self-hosted git server and injected two malicious commits. | A better-protected source code platform would have been a much harder target for the attackers.
 | C | Build with official process but from code not matching source control | [Webmin]: Attacker modified the build infrastructure to use source files not matching source control. | A SLSA-compliant build server would have produced provenance identifying the actual sources used, allowing consumers to detect such tampering.
-| D | Compromise build platform | [SolarWinds]: Attacker compromised the build platform and installed an implant that injected malicious behavior during each build. | Higher SLSA levels require [stronger security controls for the build platform](requirements.md), making it more difficult to compromise and gain persistence.
+| D | Compromise build platform | [SolarWinds]: Attacker compromised the build platform and installed an implant that injected malicious behavior during each build. | Higher SLSA levels require [stronger security controls for the build platform](requirements.md#build-requirements), making it more difficult to compromise and gain persistence.
 | E | Use bad dependency (i.e. A-H, recursively) | [event-stream]: Attacker added an innocuous dependency and then later updated the dependency to add malicious behavior. The update did not match the code submitted to GitHub (i.e. attack F). | Applying SLSA recursively to all dependencies would have prevented this particular vector, because the provenance would have indicated that it either wasn't built from a proper builder or that the source did not come from GitHub.
 | F | Upload an artifact that was not built by the CI/CD system | [CodeCov]: Attacker used leaked credentials to upload a malicious artifact to a GCS bucket, from which users download directly. | Provenance of the artifact in the GCS bucket would have shown that the artifact was not built in the expected manner from the expected source repo.
 | G | Compromise package repository | [Attacks on Package Mirrors]: Researcher ran mirrors for several popular package repositories, which could have been used to serve malicious packages. | Similar to above (F), provenance of the malicious artifacts would have shown that they were not built as expected or from the expected source repo.