l3text doc improvements

l3kernel/l3text.dtx

@@ -55,7 +55,9 @@
 % This module deals with manipulation of (formatted) text; such material is
 % comprised of a restricted set of token list content. The functions provided
 % here concern conversion of textual content for example in case changing,
-% generation of bookmarks and extraction to tags.
+% generation of bookmarks and extraction to tags. All of the major functions
+% operate by expansion. Begin-group and end-group tokens in the \meta{text}
+% are normalized and become |{| and |}|, respectively.
 %
 % \begin{function}[EXP, added = 2019-11-20]{\text_expand:n}
 %   \begin{syntax}
@@ -94,7 +96,7 @@
 %   Upper- and lowercase have the obvious meanings. Titlecasing may be regarded
 %   informally as converting the first character of the \meta{tokens} to
 %   uppercase and the rest to lowercase. However, the process is more complex
-%   than this as there are some situations where a single lower case character
+%   than this as there are some situations where a single lowercase character
 %   maps to a special form, for example \texttt{ij} in Dutch which becomes
 %   \texttt{IJ}. The \texttt{titlecase_first} variant does not attempt
 %   any case changing at all after the first letter has been processed.
@@ -114,7 +116,7 @@
 %   \end{verbatim}
 %
 %   The arguments of commands listed in \cs{l_text_case_exclude_arg_tl}
-%   and \cs{l_text_exclude_arg_tl} are exlcuded from case changing; the
+%   and \cs{l_text_exclude_arg_tl} are excluded from case changing; the
 %   latter are entirely non-textual content (such as labels).
 %
 %   As is generally true for \pkg{expl3}, these functions are designed to