improve how markdown code language is commented

We added a space between the markdown triple code mark
and language that was enclosed in HTML comments.

So a line of the form:

````
```<!---c--->
````

became:

````
``` <!---c--->
````

This was done to **help** some code see that the HTML comment
string was not a markdown code specifier.   Not all code
understands this after this changed.  For example, `pandoc(1)`
still forms HTML classes of the form "&lt;!---c--&gt;"
when it encounters the above mentioned change.

We also fixed a problem with `2019/dogon/README.md` regarding
a markdown code block.

We also fixed a problem with `2020/yang/README.md` regarding
a markdown code block.

tmp/OLD_manifest/README.md

@@ -37,7 +37,7 @@ Because the `author_handle` is used to form a JSON filename, the string must be
 lower case POSIX safe string.  Furthermore, the `author_handle` must be an ASCII
 string that matches this regexp:
 
-```<!---re-->
+``` <!---re-->
 ^[0-9a-z][0-9a-z_]*$
 ```
 
@@ -76,7 +76,7 @@ in the case of [2005/anon](/2005/anon/anon.c).
 
 Anonymous `author_handle`'s match this regexp:
 
-```<!---re-->
+``` <!---re-->
 Anonymous_[0-9][0-9][0-9][0-9][.0-9]*$
 ```
 
@@ -105,7 +105,7 @@ Non-numeric `year` strings are lower case.
 
 A `year` string matches this regexp:
 
-```<!---re-->
+``` <!---re-->
 [0-9a-z][0-9a-z][0-9a-z][0-9a-z]
 ```
 
@@ -130,7 +130,7 @@ A `dir` is a POSIX safe string that holds an winner.
 
 A `dir` is a string that matches this regexp:
 
-```<!---re-->
+``` <!---re-->
 ^[a-z][0-9a-z.-]*$
 ```
 
@@ -164,7 +164,7 @@ an `author` and the `winners` they submitted are to be listed.
 
 A `sort_word` match this regexp:
 
-```<!---re-->
+``` <!---re-->
 ^[a-z][0-9a-z]*
 ```
 
@@ -281,7 +281,7 @@ Run the script from the top level directory.  The output should end in ":1".
 
 For example, this command should not produce any output.
 
-```<!---sh-->
+``` <!---sh-->
 tmp/awards_check.sh | grep -v ':1$'
 ```
 
@@ -419,7 +419,7 @@ Temporary tool used to generate the `author/author_handle.json` files.
 
 The following command, executed in this directory, created the `author/` directory:
 
-```<!---sh-->
+``` <!---sh-->
 rm -rf ../author ; ./gen_author_json.sh  author_handle.txt author.csv author_wins.csv ../author
 ```
 

tmp/README.md

@@ -156,7 +156,7 @@ returns and appending a newline if it was missing.
 
 Fixing involves these actions:
 
-```<!---sh-->
+``` <!---sh-->
 tr -d '\015' < input.csv > tmp.csv
 echo >> tmp.csv
 mv -f tmp.csv input.csv
@@ -342,7 +342,7 @@ A tool to run another tool over all _YYYY/dir_ entry directories.
 
 Examples:
 
-```<!---sh-->
+``` <!---sh-->
 ./run_all.sh -v 3 ./fake.gen_index.sh
 ./run_all.sh -v 1 ./gen_entry_json.sh
 ```