Added const qualifier for the strings
diff --git a/contiki/apps/html-strings.h b/contiki/apps/html-strings.h
index 7c926f2..21c6c12 100644
--- a/contiki/apps/html-strings.h
+++ b/contiki/apps/html-strings.h
@@ -1,36 +1,36 @@
-extern char html_slasha[4];
-extern char html_slashcenter[9];
-extern char html_slashform[7];
-extern char html_slashh[4];
-extern char html_slashscript[9];
-extern char html_slashselect[9];
-extern char html_slashstyle[8];
-extern char html_a[3];
-extern char html_body[6];
-extern char html_br[4];
-extern char html_center[8];
-extern char html_form[6];
-extern char html_frame[7];
-extern char html_h1[4];
-extern char html_h2[4];
-extern char html_h3[4];
-extern char html_h4[4];
-extern char html_img[5];
-extern char html_input[7];
-extern char html_li[4];
-extern char html_p[3];
-extern char html_script[8];
-extern char html_select[8];
-extern char html_style[7];
-extern char html_tr[4];
-extern char html_href[6];
-extern char html_alt[5];
-extern char html_src[5];
-extern char html_type[6];
-extern char html_submit[8];
-extern char html_value[7];
-extern char html_action[8];
-extern char html_name[6];
-extern char html_text[6];
-extern char html_size[6];
-extern char html_image[7];
+extern const char html_slasha[4];
+extern const char html_slashcenter[9];
+extern const char html_slashform[7];
+extern const char html_slashh[4];
+extern const char html_slashscript[9];
+extern const char html_slashselect[9];
+extern const char html_slashstyle[8];
+extern const char html_a[3];
+extern const char html_body[6];
+extern const char html_br[4];
+extern const char html_center[8];
+extern const char html_form[6];
+extern const char html_frame[7];
+extern const char html_h1[4];
+extern const char html_h2[4];
+extern const char html_h3[4];
+extern const char html_h4[4];
+extern const char html_img[5];
+extern const char html_input[7];
+extern const char html_li[4];
+extern const char html_p[3];
+extern const char html_script[8];
+extern const char html_select[8];
+extern const char html_style[7];
+extern const char html_tr[4];
+extern const char html_href[6];
+extern const char html_alt[5];
+extern const char html_src[5];
+extern const char html_type[6];
+extern const char html_submit[8];
+extern const char html_value[7];
+extern const char html_action[8];
+extern const char html_name[6];
+extern const char html_text[6];
+extern const char html_size[6];
+extern const char html_image[7];