Revise docs (#416)

* chore: add license badge to README

* perf(docs): ignore node_modules in markdown preprocessor

* docs: remove tabs for install commands on homepage

* docs(button-set): improve copy

* docs(button): improve usage for icon-only, link buttons

* docs: various copy improvements

docs/src/components/ComponentApi.svelte

@@ -64,7 +64,7 @@
 
 <p style="margin-bottom: var(--cds-layout-02)">
   Component source code:
-  <Link size="lg" href="{source}" target="_blank">
+  <Link inline size="lg" href="{source}" target="_blank">
     {component.filePath}
     <Launch16 />
   </Link>

docs/src/components/Footer.svelte

@@ -16,7 +16,11 @@
           href="https://www.vercel.com?utm_source=carbon-components-svelte&utm_campaign=oss"
           target="_blank"
         >
-          <img src="/powered-by-vercel.svg" alt="Deploys by Vercel" />
+          <img
+            height="36px"
+            src="/powered-by-vercel.svg"
+            alt="Deploys by Vercel"
+          />
         </Link>
       </Column>
     </Row>