Move pages under tldr, lint run.sh, update docs

tldr/openbsd/pkg_add

@@ -0,0 +1,22 @@
+---
+syntax: markdown
+tags: [tldr, openbsd]
+source: https://github.com/tldr-pages/tldr.git
+---
+# pkg_add
+
+> Install/update packages in OpenBSD.
+> See also: `pkg_info`, `pkg_delete`.
+> More information: <https://man.openbsd.org/pkg_add>.
+
+- Update all packages, including dependencies:
+
+`pkg_add -u`
+
+- Install a new package:
+
+`pkg_add {{package}}`
+
+- Install packages from the raw output of `pkg_info`:
+
+`pkg_add -l {{path/to/file}}`