Fix capitalization of "Tcl"

doc/src/sgml/install-windows.sgml

@@ -205,7 +205,7 @@ $ENV{MSBFLAGS}="/m";
 
    <variablelist>
     <varlistentry>
-     <term><productname>ActiveState TCL</productname></term>
+     <term><productname>ActiveState Tcl</productname></term>
      <listitem><para>
       Required for building <application>PL/Tcl</application> (Note: version
       8.4 is required, the free Standard Distribution is sufficient).

doc/src/sgml/xact.sgml

@@ -122,7 +122,7 @@
    Subtransactions can be started explicitly using the
    <command>SAVEPOINT</command> command, but can also be started in
    other ways, such as PL/pgSQL's <literal>EXCEPTION</literal> clause.
-   PL/Python and PL/TCL also support explicit subtransactions.
+   PL/Python and PL/Tcl also support explicit subtransactions.
    Subtransactions can also be started from other subtransactions.
    The top-level transaction and its child subtransactions form a
    hierarchy or tree, which is why we refer to the main transaction as

src/pl/tcl/pltcl.c

@@ -334,7 +334,7 @@ static void pltcl_init_tuple_store(pltcl_call_state *call_state);
 /*
  * Hack to override Tcl's builtin Notifier subsystem.  This prevents the
  * backend from becoming multithreaded, which breaks all sorts of things.
- * That happens in the default version of Tcl_InitNotifier if the TCL library
+ * That happens in the default version of Tcl_InitNotifier if the Tcl library
  * has been compiled with multithreading support (i.e. when TCL_THREADS is
  * defined under Unix, and in all cases under Windows).
  * It's okay to disable the notifier because we never enter the Tcl event loop