Refine cords README regarding summary and build

* docs/README.cords: Slightly refine summary about library headers;
refine information about cord library build.

docs/README.cords

@@ -1,14 +1,17 @@
+Cords package
+-------------
 
-This is a string package that uses a tree-based representation.
-See cord.h for a description of the functions provided.  Ec.h describes
-"extensible cords", which are essentially output streams that write
-to a cord.  These allow for efficient construction of cords without
+Cords package (also known as "cord library") is a string package that uses
+a tree-based representation.
+
+See cord.h for a description of the basic functions provided.  And, ec.h
+describes "extensible cords", those are essentially output streams that write
+to a cord; these allow for efficient construction of cords without
 requiring a bound on the size of a cord.
 
-The cord library is built by default in case of the GNU autoconf-based build
-and the CMake-based one (unless "-Dbuild_cord=OFF" option is given to cmake).
-If you wish to build the library with the stand-alone Makefile.direct, type
-"make -f Makefile.direct cords".
+The cord library is built along with gc library by default unless manually
+disabled (e.g., in case of cmake-based build, unless "-Dbuild_cord=OFF" option
+is passed to cmake).
 
 More details on the data structure can be found in: