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

tldr/linux/groupadd

@@ -0,0 +1,22 @@
+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# groupadd
+
+> Add user groups to the system.
+> See also: `groups`, `groupdel`, `groupmod`.
+> More information: <https://manned.org/groupadd>.
+
+- Create a new group:
+
+`sudo groupadd {{group_name}}`
+
+- Create a new system group:
+
+`sudo groupadd --system {{group_name}}`
+
+- Create a new group with the specific groupid:
+
+`sudo groupadd --gid {{id}} {{group_name}}`