coreutils commands: move pages to common/ folder (#2442)

pages/common/head.md

@@ -0,0 +1,19 @@
+# head
+
+> Output the first part of files.
+
+- Output the first few lines of a file:
+
+`head -n {{count_of_lines}} {{filename}}`
+
+- Output the first few bytes of a file:
+
+`head -c {{size_in_bytes}} {{filename}}`
+
+- Output everything but the last few lines of a file:
+
+`head -n -{{count_of_lines}} {{filename}}`
+
+- Output everything but the last few bytes of a file:
+
+`head -c -{{size_in_bytes}} {{filename}}`