Base: Add uptime(1) manpage

Base/usr/share/man/man1/uptime.md

@@ -0,0 +1,16 @@
+## Name
+
+uptime - Tell how long the system has been running
+
+## Synopsis
+
+```sh
+$ uptime
+```
+
+## Examples
+
+```sh
+$ uptime
+Up 2 minutes, 20 seconds
+```