Fixing typo in docs

Thanks to a former colleague for pointing this out.

Author: matt-bernhardt

README.md

@@ -10,7 +10,7 @@ The backend is populated via [pipelines](https://github.com/MITLibraries/mario).
 ## Architecture Decision Records
 
 This repository contains Architecture Decision Records in the
-[docs/architecture-decisions directory](docs/architecture_decisions).
+[docs/architecture-decisions directory](docs/architecture-decisions).
 
 [adr-tools](https://github.com/npryce/adr-tools) should allow easy creation of
 additional records with a standardized template.