docs: how to release a library

Signed-off-by: Carlos Alexandro Becker <caarlos0@gmail.com>

www/docs/cookbooks/release-a-library.md

@@ -0,0 +1,10 @@
+# How to release a library
+
+Maybe you don't want to actually release binaries, but just generate a changelog and whatnot for your Go libraries? GoReleaser got you covered!
+
+All you need is to add `skip: true` to the build config:
+
+```yaml
+builds:
+- skip: true
+```

www/mkdocs.yml

@@ -86,6 +86,7 @@ nav:
 - Cookbooks:
   - About: cookbooks/index.md
   - cookbooks/semantic-release.md
+  - cookbooks/release-a-library.md
 - tutorials.md
 - links.md