fix HTML problems associated with leading ---'s

Please do not use "**---**" in markdown lines to separate sections.

This causes `pandoc(1)` to generate "**\<hr />**".

The "**\<hr />**" has no effect in standard HTML 5 and interacts
badly with unquoted attribute values.

If a horizontal line is really needed, use "**\<hr>**".

If a short line is needed, use: "**\<hr
style="width:10%;text-align:left;margin-left:0">**"

1992/gson/README.md

@@ -151,7 +151,7 @@ Here follows a description of some of the data structures and
 algorithms used by AG.  It is by no means complete, but it may help
 you get an idea about the general principles.
 
----
+<hr style="width:10%;text-align:left;margin-left:0">
 
 Internally, AG represents words and sentences as arrays of 32
 4-bit integer elements.  Each element represents the number of