Fix make and makefile in README.md files

That is

    sgit -e 's/Use make\( to compile\)/Use `make`\1/g' -e \
     's/makefile/Makefile/g'  '20[0-9][0-9]/README.md'

This way 'make' is formatted with a code block (or whatever the term is
in markdown terminology) and 'makefile' is changed to Makefile.

BTW: fun fact: Landon was part of the recommendation of naming Makefiles
Makefile instead of makefile which is shown in the man page make(1):

    Normally you should call your makefile either makefile or Makefile.
    (We recommend Makefile because it appears prominently near the
    beginning of a directory listing, right near other important files
    such as README.) The first name checked, GNUmakefile, is not
    recommended for most makefiles.  You should use this name if you
    have a makefile that is specific to GNU Make, and will not be
    understood by other versions of make.  If makefile is '-', the
    standard input is read.

2001/README.md

@@ -10,10 +10,10 @@ You may then wish to look at the Author's remarks for even more details.
 The IOCCC has a web site and now has a number of international mirrors.  The
 primary site can be found at <https://www.ioccc.org>.
 
-Use make to compile entries.  It is possible that on non-Unix / non-Linux
-systems the makefile needs to be changed.  See the Makefile for details.
+Use `make` to compile entries.  It is possible that on non-Unix / non-Linux
+systems the Makefile needs to be changed.  See the Makefile for details.
 
-Read over the makefile for compile/build issues.  Your system may
+Read over the Makefile for compile/build issues.  Your system may
 require certain changes (add or remove a library, add or remove a
 #define).
 
@@ -22,8 +22,7 @@ yours is lacking, you may need to compile using gcc instead of your
 local compiler.
 
 
-Remarks on some of the entries
-------------------------------
+## Remarks on some of the entries
 
 There were some outstanding entries that did not win.  Unfortunately
 some very good entries lost because they: