freebsd, netbsd: add directory; pkg, pkgin: add page (#11313)

* freebsd: add directory; pkg: add page

* netbsd: add directory; pkgin: add page

* pkg, pkgin: move install and remove examples to the top

* pkgin: add backticks `pkgsrc`

Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>

---------

Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>

pages/netbsd/pkgin.md

@@ -0,0 +1,28 @@
+# pkgin
+
+> Manage `pkgsrc` binary packages on NetBSD.
+> More information: <https://pkgin.net/#usage>.
+
+- Install a package:
+
+`pkgin install {{package}}`
+
+- Remove a package and its dependencies:
+
+`pkgin remove {{package}}`
+
+- Upgrade all packages:
+
+`pkgin full-upgrade`
+
+- Search for a package:
+
+`pkgin search {{keyword}}`
+
+- List installed packages:
+
+`pkgin list`
+
+- Remove unneeded dependencies:
+
+`pkgin autoremove`