perlxs.pod: update BOOT: keyword

Author: iabyn

dist/ExtUtils-ParseXS/lib/perlxs.pod

@@ -1876,20 +1876,19 @@ typemaps.
 
 =head3 The BOOT: Keyword
 
-The BOOT: keyword is used to add code to the extension's bootstrap
-function.  The bootstrap function is generated by the B<xsubpp> compiler and
-normally holds the statements necessary to register any XSUBs with Perl.
-With the BOOT: keyword the programmer can tell the compiler to add extra
-statements to the bootstrap function.
-
-This keyword may be used any time after the first MODULE keyword and should
-appear on a line by itself.  The first blank line after the keyword will
-terminate the code block.
-
     BOOT:
-      # The following message will be printed when the
-      # bootstrap function executes.
-      printf("Hello from the bootstrap!\n");
+        # Print a message when the module is loaded
+        printf("Hello from the bootstrap!\n");
+
+The C<BOOT> keyword is used to add code to the extension's bootstrap
+function. This function is generated by the XS parser and normally holds
+the statements necessary to register any XSUBs with Perl. It is usually
+called once, at C<use Foo::Bar> time.
+
+This keyword should appear on a line by itself. All subsequent lines will
+be interpreted as lines of C code to pass through, including C
+preprocessor directives, but excluding POD and C<#> comments; until the
+next keyword or possible start of a new XSUB (C</\n\n\S/>).
 
 =head3 The FALLBACK: Keyword