doc: fix pdf and info pages generation

doc/conf.py.in

@@ -183,7 +183,7 @@ latex_elements = {
 # Grouping the document tree into LaTeX files. List of tuples
 # (source start file, target name, title, author, documentclass [howto/manual]).
 latex_documents = [
-  ('knot', 'KnotDNS.tex', u'Knot DNS Documentation',
+  ('index', 'KnotDNS.tex', u'Knot DNS Documentation',
    u'CZ.NIC, z.s.p.o.', 'manual'),
 ]
 
@@ -227,7 +227,7 @@ latex_documents = [
 # (source start file, target name, title, author,
 #  dir menu entry, description, category)
 texinfo_documents = [
-  ('knot', 'KnotDNS', u'Knot DNS Documentation',
+  ('index', 'KnotDNS', u'Knot DNS Documentation',
    u'CZ.NIC, z.s.p.o.', 'KnotDNS',
    'High-performance authoritative DNS server implementation',
    'Miscellaneous'),