corrects the wgetrc path from /usr/local/etc/ to /etc/wgetrc in the sample wgetrc

--- a/doc/sample.wgetrc
+++ b/doc/sample.wgetrc
@@ -10,7 +10,7 @@
 ## Or online here:
 ##   https://www.gnu.org/software/wget/manual/wget.html#Startup-File
 ##
-## Wget initialization file can reside in /usr/local/etc/wgetrc
+## Wget initialization file can reside in /etc/wgetrc
 ## (global, for all users) or $HOME/.wgetrc (for a single user).
 ##
 ## To use the settings in this file, you will have to uncomment them,
@@ -19,7 +19,7 @@
 
 
 ##
-## Global settings (useful for setting up in /usr/local/etc/wgetrc).
+## Global settings (useful for setting up in /etc/wgetrc).
 ## Think well before you change them, since they may reduce wget's
 ## functionality, and make it behave contrary to the documentation:
 ##