gnu: Fix typos in descriptions.

gnu: Fix typos in descriptions.

* gnu/packages/admin.scm (di)[description]: Likewise.
* gnu/packages/bioinformatics.scm (r-annotate)[description]: Likewise.
* gnu/packages/datastructures.scm (sparsehash)[description]: Likewise.
* gnu/packages/dns.scm (knot)[description]: Likewise.
* gnu/packages/emacs.scm (emacs-idle-highlight)[synopsis, description]:
Likewise.
* gnu/packages/gnome.scm (libpeas)[description]: Likewise.
* gnu/packages/gtk.scm (python2-pygtk)[description]: Likewise.
* gnu/packages/kde-frameworks.scm (kactivities)[description]: Fix typo.
* gnu/packages/libevent.scm (perl-anyevent)[description]: Likewise.
* gnu/packages/machine-learning.scm (ghmm)[description]: Likewise.
* gnu/packages/mail.scm (mlmmj)[description]: Likewise.
* gnu/packages/maths.scm (vc)[description]: Likewise.
* gnu/packages/music.scm (gx-super-fuzz-lv2)[description]: Likewise.
* gnu/packages/networking.scm (nload)[description]: Likewise.
* gnu/packages/python.scm (python-execnet)[description]: Likewise.
* gnu/packages/terminals.scm (tilda)[description]: Likewise.
* gnu/packages/python.scm (python-execnet, python-tables)
(python2-coverage-test-runner, python2-rope)[description]: Likewise.