[tldoc] top-level README update for TeX Live

[Karl Berry]

Also: one change was necessary to the top-level README (that is, the
files in Master/readme-{html,txt}.dir/) ... install-tl.bat is now named
install-tl-windows.bat.  I also changed one pronoun (seemed clearer to
me).

Thanks,
Karl

--- readme-txt.dir/README.EN    (revision 33794)
+++ readme-txt.dir/README.EN    (working copy)
@@ -20,7 +20,7 @@
    description of the top-level directories, and more.

    If you are installing from the DVD image, the Guide in English and all
-   the translations are in the [3]texlive-doc subdirectory.
+   its translations are in the [3]texlive-doc subdirectory.

    After installation, English versions of the Guide are in the
    [4]texmf-dist/doc/texlive/ hierarchy, in both [5]html and [6]pdf
@@ -39,7 +39,7 @@

   Installation

-   The installation script is named install-tl (install-tl.bat on
+   The installation script is named install-tl (install-tl-windows.bat on
    Windows), and it has three operation modes: