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

tldr/linux/checkupdates

@@ -0,0 +1,25 @@
+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# checkupdates
+
+> Check pending updates in Arch Linux.
+> More information: <https://man.archlinux.org/man/checkupdates.8>.
+
+- List pending updates:
+
+`checkupdates`
+
+- List pending updates and download the packages to the `pacman` cache:
+
+`checkupdates --download`
+
+- List pending updates using a specific `pacman` database:
+
+`CHECKUPDATES_DB={{path/to/directory}} checkupdates`
+
+- Display help:
+
+`checkupdates --help`