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.

2000/README.md

@@ -8,10 +8,10 @@ on how to compile it and how to run the winning program.
 Look at the winning source and try to figure how it does what it does!
 You may then wish to look at the Author's remarks for even more 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.
+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).