doc: cosmetic fixes

src/doc/manual/developer-guide/objects.txi

@@ -65,7 +65,7 @@ type of object. For instance, a cons cell consists of three words:
 
 @cfindex --enable-small-cons [YES|no]
 
-Note, that this is on of the possible implementations of
+Note, that this is one of the possible implementation of
 @code{cons}. The second one (currently default) uses the immediate value
 for the @code{list} and consumes two words instead of three. Such
 implementation is more memory and speed efficient (according to the

src/doc/manual/introduction/about_man.txi

@@ -12,20 +12,20 @@ purpose. The homepage of the
 @uref{https://common-lisp.net,Common-Lisp.net} contains a good list of
 links of such teaching and learning material.
 
-This book is structure into four parts:
+This book is structured into four parts:
 
 @subsection User's guide
 We begin with [@ref{User's guide}] which provides introductory material
 showing the user how to build and use ECL and some of its unique
 features. This part assumes some basic Common Lisp knowledge and is
-suggested as an entry point for a new users who want to start using
+suggested as an entry point for new users who want to start using
 @ecl{}.
 
 @subsection Developer's guide
 [@ref{Developer's guide}] documents @ecl{} implementation details. This
 part is not meant for normal users but rather for the ECL developers
 and other people who want to contribute to @ecl{}. This section is prone
-to change due to the dynamic nature of a software. Covered topics
+to change due to the dynamic nature of the software. Covered topics
 include source code structure, contributing guide, internal
 implementation details and many other topics relevant to the development
 process.

src/doc/manual/user-guide/building.txi

@@ -1,7 +1,7 @@
 @node Building ECL
 @section Building ECL
 
-Due to its portable nature ECL works on every (at least) 32-bit
+Due to its portable nature, ECL works on every (at least) 32-bit
 architecture which provides a proper C99 compliant compiler.
 
 Operating systems on which ECL is reported to work: Linux, Darwin (Mac

src/doc/manual/user-guide/invoking.txi

@@ -62,8 +62,10 @@ To exit from @ecl{}, call the function @coderef{ext:quit}.
 %
 @end example
 
-Alternatively, you may type @code{^D} , i.e. press the key @key{D}
-while pressing down the control key (@key{Ctrl}).
+Alternatively, you may type @code{^D} on UNIX-like operating systems,
+i.e. press the key @key{D}
+while pressing down the control key (@key{Ctrl}),
+on Windows, you should use @code{^Z} followed by a return.
 
 @example
 > @myctrl{D}