A number of docstring fixes

A number of docstring fixes

* lisp/net/dictionary.el (dictionary-set-server-var, dictionary-mode,
  dictionary, dictionary-new-buffer, dictionary-reply-code,
  dictionary-reply, dictionary-reply-list, dictionary-open-server,
  dictionary-check-connection, dictionary-mode-p, dictionary-close,
  dictionary-read-reply, dictionary-split-string,
  dictionary-read-reply-and-split, dictionary-read-answer,
  dictionary-check-reply, dictionary-coding-system,
  dictionary-decode-charset, dictionary-encode-charset,
  dictionary-check-initial-reply, dictionary-store-state,
  dictionary-restore-state, dictionary-new-search,
  dictionary-new-search-internal, dictionary-do-search,
  dictionary-pre-buffer, dictionary-post-buffer,
  dictionary-display-search-result, dictionary-display-word-entry,
  dictionary-display-word-definition, dictionary-mark-reference,
  dictionary-select-dictionary, dictionary-display-dictionarys,
  dictionary-display-dictionary-line, dictionary-set-dictionary,
  dictionary-special-dictionary, dictionary-display-more-info,
  dictionary-select-strategy, dictionary-do-select-strategy,
  dictionary-display-strategies, dictionary-display-strategy-line,
  dictionary-set-strategy, dictionary-new-matching,
  dictionary-do-matching, dictionary-display-only-match-result,
  dictionary-display-match-result, dictionary-display-match-result,
  dictionary-display-match-lines, dictionary-search,
  dictionary-previous, dictionary-help, dictionary-match-words,
  dictionary-mouse-popup-matching-words,
  dictionary-popup-matching-words, dictionary-tooltip-mode,
  dictionary-tooltip-mouse-event): Fix docstring

The following kind of changes were made:

- finish first line with a full stop (.)
- mention parameter in upper-case whenever possible (considering the
  length constraints)