Fix typo in makefile.

Dependencies

• [2] 6U6KBFYP Build the HTML manual; add the HTML & PDF to the distribution; install them.
• [3] FV2M6MOT hydra: use autoconf/-make

Change contents

• replacement in doc/manual/Makefile.am at line 19
  [2.693]→[2.693:751](∅→∅)
  − @echo "Please install xsltproc and rerun configure."; \
  [2.693]

  [2.751]
  + echo "Please install xsltproc and rerun configure."; \