docs/man/nut_usb_addvars.txt, docs/man/ups.conf.txt: fix links leading to libusb API docs with two underscores

Signed-off-by: Jim Klimov <jimklimov+nut@gmail.com>

Author: jimklimov

docs/man/nut_usb_addvars.txt

@@ -142,4 +142,9 @@ For more details, including the currently supported values for your version
 of the library, see e.g.:
 
 * https://libusb.sourceforge.io/api-1.0/
-* link:https://libusb.sourceforge.io/api-1.0/group__libusb__lib.html[https://libusb.sourceforge.io/api-1.0/group\__libusb__lib.html]
+* link:https://libusb.sourceforge.io/api-1.0/group\__libusb\__lib.html[https://libusb.sourceforge.io/api-1.0/group\__libusb__lib.html]
+
+///////////////////
+// EDITOR NOTE: There are no backslashes in the URL above, just that
+// asciidoc sees them as "emphasis" markup, they had to be escaped.
+///////////////////

docs/man/ups.conf.txt

@@ -199,7 +199,12 @@ For more details, including the currently supported values for your
 version of the library, see e.g.:
 
 * https://libusb.sourceforge.io/api-1.0/
-* https://libusb.sourceforge.io/api-1.0/group__libusb__lib.html
+* link:https://libusb.sourceforge.io/api-1.0/group\__libusb\__lib.html[https://libusb.sourceforge.io/api-1.0/group\__libusb__lib.html]
+
+///////////////////
+// EDITOR NOTE: There are no backslashes in the URL above, just that
+// asciidoc sees them as "emphasis" markup, they had to be escaped.
+///////////////////
 
 UPS FIELDS
 ----------
@@ -405,7 +410,12 @@ For more details, including the currently supported values for your
 version of the library, see e.g.:
 
 * https://libusb.sourceforge.io/api-1.0/
-* https://libusb.sourceforge.io/api-1.0/group__libusb__lib.html
+* link:https://libusb.sourceforge.io/api-1.0/group\__libusb\__lib.html[https://libusb.sourceforge.io/api-1.0/group\__libusb__lib.html]
+
+///////////////////
+// EDITOR NOTE: There are no backslashes in the URL above, just that
+// asciidoc sees them as "emphasis" markup, they had to be escaped.
+///////////////////
 
 INTEGRATION
 -----------