yash: doc: typographical, grammatical, and semantical fixes

Patch sent by Sergey Romanov

git-svn-id: svn+ssh://svn.sourceforge.jp/svnroot/yash/yash/trunk@3182 048f04df-13f5-43d7-8114-9f9ceecaec24
yash: doc: いろいろ修正

git-svn-id: svn+ssh://svn.sourceforge.jp/svnroot/yash/yash/trunk@3183 048f04df-13f5-43d7-8114-9f9ceecaec24