Homepage: Add buttons to go to schema specifications

Author: ewels

docs/index.md

@@ -15,6 +15,9 @@ description: Nextflow plugin for sample sheet validation
 
     nf-schema is the new version of the now deprecated [nf-validation](https://github.com/nextflow-io/nf-validation). Please follow the [migration guide](https://nextflow-io.github.io/nf-schema/latest/migration_guide/) to migrate your code to this new version.
 
+[Parameter schema specs](nextflow_schema/nextflow_schema_specification/){ .md-button .md-button--primary }
+[Sample sheet schema specs](nextflow_schema/sample_sheet_schema_specification/){ .md-button }
+
 ## Introduction
 
 --8<-- "README.md:11:"

mkdocs.yml

@@ -69,6 +69,7 @@ extra_css:
 
 markdown_extensions:
   - admonition
+  - attr_list
   - def_list
   - md_in_html
   - pymdownx.emoji: