Fix some grammatical errors in the manual

doc/src/manual/cowboy_req.read_body.asciidoc

@@ -79,7 +79,7 @@ been read, or there was no body to begin with.
 
 The data is always returned as a binary.
 
-The Req object returned in the tuple must be used for that point
+The Req object returned in the tuple must be used from that point
 onward. It contains a more up to date representation of the request.
 For example it may have an added content-length header once the
 body has been read.

doc/src/manual/cowboy_req.read_part.asciidoc

@@ -74,7 +74,7 @@ as a map.
 
 A `done` tuple is returned if there are no more parts to read.
 
-The Req object returned in the tuple must be used for that point
+The Req object returned in the tuple must be used from that point
 onward. It contains a more up to date representation of the request.
 For example it may have an added content-length header once the
 body has been read.

doc/src/manual/cowboy_req.read_part_body.asciidoc

@@ -61,7 +61,7 @@ An `ok` tuple is returned when there are no more data to be read.
 
 The data is always returned as a binary.
 
-The Req object returned in the tuple must be used for that point
+The Req object returned in the tuple must be used from that point
 onward. It contains a more up to date representation of the request.
 For example it may have an added content-length header once the
 body has been read.

doc/src/manual/cowboy_req.read_urlencoded_body.asciidoc

@@ -60,7 +60,7 @@ to 5 seconds.
 An `ok` tuple is returned containing a list of key/values found
 in the body.
 
-The Req object returned in the tuple must be used for that point
+The Req object returned in the tuple must be used from that point
 onward. It contains a more up to date representation of the request.
 For example it may have an added content-length header once the
 body has been read.