doxygen: move related files to doc/doxygen

Doxyfile.in

@@ -694,7 +694,7 @@ FILE_VERSION_FILTER    =
 # DoxygenLayout.xml, doxygen will parse it automatically even if the LAYOUT_FILE
 # tag is left empty.
 
-LAYOUT_FILE            = DoxygenLayout.xml
+LAYOUT_FILE            = doc/doxygen/DoxygenLayout.xml
 
 # The CITE_BIB_FILES tag can be used to specify one or more bib files containing
 # the reference definitions. This must be a list of .bib files. The .bib
@@ -781,7 +781,7 @@ WARN_LOGFILE           = doc/html/doxygen.warn
 # spaces. See also FILE_PATTERNS and EXTENSION_MAPPING
 # Note: If this tag is empty the current directory is searched.
 
-INPUT                  = Doxy.page.h \
+INPUT                  = doc/doxygen/Doxy.page.h \
                          src/libdnssec \
                          src/libknot \
                          src/libzscanner \