add quota.md (fixes #832)

pages/common/quota.md

@@ -0,0 +1,18 @@
+# quota
+
+> Display users' disk space usage and allocated limits.
+
+- Show disk quotas for the current user:
+`quota`
+
+- Verbose output (also display quotas on filesystems where no storage is allocated)
+`quota -v`
+
+- Quiet output (only display quotas on filesystems where usage is over quota)
+`quota -q`
+
+- Print quotas for the groups of which the current user is a member:
+`quota -g`
+
+- Show disk quotas for another user (must be superuser to do this):
+`sudo quota -u {{username}}`