Update changelogs from fern repo (#5418)

Co-authored-by: dsinghvi <10870189+dsinghvi@users.noreply.github.com>

Author: fern-support

fern/products/cli-api-reference/cli-changelog/2026-05-07.mdx

@@ -0,0 +1,9 @@
+## 5.18.0
+**`(feat):`** Add `fern schema [name]` command (CLI v2) that emits a JSON Schema for
+`fern.yml`. Running `fern schema` with no argument prints the full schema;
+passing a dot-delimited subsection (e.g. `fern schema sdks`,
+`fern schema sdks.targets`, `fern schema api`) prints just that block.
+Intended primarily for AI agents that need to generate or validate Fern
+config at runtime without consulting external docs.
+
+