README: Add links to SPDX specs and Javadocs

Signed-off-by: Arthit Suriyawongkul <arthit@gmail.com>

Author: bact

README.md

@@ -1,30 +1,39 @@
 # Spdx-Java-Rdf-Store
 
-This Java library implements an RDF store supported SPDX spec version 2.3 and earlier implementing the [SPDX Java Library Storage Interface](https://github.com/spdx/Spdx-Java-Library#storage-interface) using an underlying RDF store.
+This Java library implements an RDF store supported [SPDX spec version 2.3][spdx2.3] and earlier implementing the [SPDX Java Library Storage Interface][storage] using an underlying RDF store.
 
-# Code quality badges
+[spdx2.3]: https://spdx.github.io/spdx-spec/v2.3/
+[storage]: https://github.com/spdx/Spdx-Java-Library#storage-interface
 
-|   [![Bugs](https://sonarcloud.io/api/project_badges/measure?project=spdx-rdf-store&metric=bugs)](https://sonarcloud.io/dashboard?id=spdx-rdf-store)    | [![Security Rating](https://sonarcloud.io/api/project_badges/measure?project=spdx-rdf-store&metric=security_rating)](https://sonarcloud.io/dashboard?id=spdx-rdf-store) | [![Maintainability Rating](https://sonarcloud.io/api/project_badges/measure?project=spdx-rdf-store&metric=sqale_rating)](https://sonarcloud.io/dashboard?id=spdx-rdf-store) | [![Technical Debt](https://sonarcloud.io/api/project_badges/measure?project=spdx-rdf-store&metric=sqale_index)](https://sonarcloud.io/dashboard?id=spdx-rdf-store) |
+## Code quality badges
 
-# Using the Library
+[![Bugs](https://sonarcloud.io/api/project_badges/measure?project=spdx-rdf-store&metric=bugs)](https://sonarcloud.io/dashboard?id=spdx-rdf-store)
+[![Security Rating](https://sonarcloud.io/api/project_badges/measure?project=spdx-rdf-store&metric=security_rating)](https://sonarcloud.io/dashboard?id=spdx-rdf-store)
+[![Maintainability Rating](https://sonarcloud.io/api/project_badges/measure?project=spdx-rdf-store&metric=sqale_rating)](https://sonarcloud.io/dashboard?id=spdx-rdf-store)
+[![Technical Debt](https://sonarcloud.io/api/project_badges/measure?project=spdx-rdf-store&metric=sqale_index)](https://sonarcloud.io/dashboard?id=spdx-rdf-store)
+
+## Using the Library
 
 This library is intended to be used in conjunction with the [SPDX Java Library](https://github.com/spdx/Spdx-Java-Library).
 
 Simply create a new instance of `RdfStore(documentNamespace)` and reference it as your storage.  The documentNamespace is the namespace used for the store.
 
-Note that this version of the RDF library only supports a single document namespace and DOES NOT support spec versions 3.0 and later.
+Note that this version of the RDF library only supports a single document namespace and DOES NOT support [SPDX spec versions 3.0][spdx3.0] and later.
+
+[spdx3.0]: https://spdx.github.io/spdx-spec/v3.0/
 
-# Serializing and Deserializing RDF Formats
+## Serializing and Deserializing RDF Formats
 
-This library supports the `ISerializableModelStore` interface for serializing and deserializing RDF files and data stores.
+This library supports the [`ISerializableModelStore`][ISerializableModelStore] interface for serializing and deserializing RDF files and data stores.
 
 The format is specified by calling the `setOutputFormat(OutputFormat outputFormat)` method.
 
 OutputFormat must be one of RDF/XML-ABBREV (default), RDF/XML, N-TRIPLET, or TURTLE.
 
 A convenience method `public String loadModelFromFile(String fileNameOrUrl, boolean overwrite)` can be used to load the model from a file or URL.
 
-# Development Status
+[ISerializableModelStore]: https://spdx.github.io/spdx-java-core/org/spdx/storage/ISerializableModelStore.html
 
-Less stable - it has just been updated to support the redesigned storage interfaces.
+## Development Status
 
+Less stable - it has just been updated to support the redesigned storage interfaces.