Update README.md

README.md

@@ -25,7 +25,7 @@ The **Ontology of units of Measure (OM) 2.0** models concepts and relations that
 
 <!-- ## <a name="om"></a>Ontology of units of Measure (OM) -->
 
-## <a name="overview"></a>Overview
+## <a name="concepts"></a>Concepts
 
 The OM ontology provides classes, instances, and properties that represent the different concepts used for defining and using units, quantities and related concepts. It includes, for instance, common units such as the SI units metre (`om:metre`) and kilogram (`om:kilogram`), as well as units from other systems of units, such as the mile (`om:mile`) and the nautical mile (`om:nauticalMile-International`). For a range of application areas it includes specific units and quantities, such as the unit of the Hubble constant – a compound unit –, km/s/Mpc (`om:kilometrePerSecond-TimePerMegaparsec`), and the quantity 'viable count' (`om:ViableCount`).