Feat: Add `cgmem_which`

Show in what memory control group the current shell is.

diff --git a/bin/cgmem_which b/bin/cgmem_which
new file mode 100755 (executable)
index 0000000..81ef03f
--- /dev/null
+++ b/bin/cgmem_which
@@ -0,0 +1,2 @@
+#! /bin/sh
+grep -Flw $$ /sys/fs/cgroup/*/tasks | cut -d/ -f5