Changing heading level of 'Alternate code'

Change level 3 (###) to level 2 (##):

    sgit -e 's/^### \(Alternate code\)/## \1/g' '*README.md'

which is the same as:

    sgit -e 's/^### Alternate code/## Alternate code/g' '*README.md'

This is per discussion in GitHub.

1988/applin/README.md

@@ -21,7 +21,7 @@ program.  See the [Alternate code](#alternate-code) section below for details.
 ./applin
 ```
 
-### Alternate code:
+## Alternate code:
 
 As noted above a smaller version can be used in case your `cpp` has a hard time
 with this entry.

1988/dale/README.md

@@ -38,7 +38,7 @@ behaviour?
 ./dale "$(printf "the following files exist in this directory:\n%s\n" *)"
 ```
 
-### Alternate code:
+## Alternate code:
 
 If you have an old enough compiler you can try the original version in
 [dale.alt.c](dale.alt.c). To use:

1988/isaak/README.md

@@ -19,7 +19,7 @@ code](#alternate-code) below.
 ./isaak
 ```
 
-### Alternate code:
+## Alternate code:
 
 The original version of this code is in [isaak.alt.c](isaak.alt.c).
 The original entry starts with the line:

1988/litmaath/README.md

@@ -24,7 +24,7 @@ code](#alternate-code) section below.
 ./litmaath eschew obfuscation
 ```
 
-### Alternate code:
+## Alternate code:
 
 
 This alternate code, added to help understand the entry and for fun, is code

1988/westley/README.md

@@ -55,7 +55,7 @@ You might enjoy looking at the output of:
 cc -E westley.alt.c
 ```
 
-### Alternate code:
+## Alternate code:
 
 To see if your compiler has the problem described above try: