Revise the style of a paragraph in README.md.

Presently, one of the lines in README.md has trailing whitespace,
which was added by commit 363eb05 to maintain a line break that
was in the non-Markdown version.  Instead of changing
.gitattributes, let's match this paragraph's style with the style
of the following paragraph, thereby removing the trailing
whitespace.

Reported-by: Peter Eisentraut
Reviewed-by: Daniel Gustafsson
Discussion: https://postgr.es/m/c0a4e906-c6fe-4519-bd15-28dfcd03fdb2%40eisentraut.org

Author: nathan-bossart

README.md

@@ -11,11 +11,10 @@ and functions.  This distribution also contains C language bindings.
 
 Copyright and license information can be found in the file COPYRIGHT.
 
-General documentation about this version of PostgreSQL can be found at:
-<https://www.postgresql.org/docs/devel/>  
-In particular, information about building PostgreSQL from the source
-code can be found at:
-<https://www.postgresql.org/docs/devel/installation.html>
+General documentation about this version of PostgreSQL can be found at
+<https://www.postgresql.org/docs/devel/>.  In particular, information
+about building PostgreSQL from the source code can be found at
+<https://www.postgresql.org/docs/devel/installation.html>.
 
 The latest version of this software, and related software, may be
 obtained at <https://www.postgresql.org/download/>.  For more information