Update cheatsheets

tldr/linux/spa-json-dump

@@ -0,0 +1,17 @@
+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# spa-json-dump
+
+> Convert a SPA JSON file to standard JSON.
+> More information: <https://docs.pipewire.org/page_man_spa-json-dump_1.html>.
+
+- Convert a SPA JSON file to standard JSON:
+
+`spa-json-dump {{path/to/file.conf}}`
+
+- Convert SPA JSON from `stdin` to standard JSON:
+
+`echo "{{spa_json_string}}" | spa-json-dump`