microsite: set UR redirects for core features

We already have a redirect in place i.e. /docs to /docs/overview/what-is-backstage/

This PR adds 3 new redirects
/docs/features/software-catalog -> /docs/features/software-catalog/software-catalog-overview
/docs/features/techdocs -> /docs/features/techdocs/techdocs-overview
/docs/features/software-templates -> /docs/features/software-templates/software-templates-index

microsite/pages/en/docs/features/software-catalog/index.js

@@ -0,0 +1,12 @@
+const React = require('react');
+const Redirect = require('../../../../../core/Redirect.js');
+
+const siteConfig = require(process.cwd() + '/siteConfig.js');
+
+function Docs() {
+  return (
+    <Redirect redirect="/docs/features/software-catalog/software-catalog-overview" config={siteConfig} />
+  );
+}
+
+module.exports = Docs;

microsite/pages/en/docs/features/software-templates/index.js

@@ -0,0 +1,12 @@
+const React = require('react');
+const Redirect = require('../../../../../core/Redirect.js');
+
+const siteConfig = require(process.cwd() + '/siteConfig.js');
+
+function Docs() {
+  return (
+    <Redirect redirect="/docs/features/software-templates/software-templates-index" config={siteConfig} />
+  );
+}
+
+module.exports = Docs;

microsite/pages/en/docs/features/techdocs/index.js

@@ -0,0 +1,12 @@
+const React = require('react');
+const Redirect = require('../../../../../core/Redirect.js');
+
+const siteConfig = require(process.cwd() + '/siteConfig.js');
+
+function Docs() {
+  return (
+    <Redirect redirect="/docs/features/techdocs/techdocs-overview" config={siteConfig} />
+  );
+}
+
+module.exports = Docs;