[glibmm] Glib::OptionGroup: Improve the documentation of add_entry()

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 875b7b10167a626d1bf9eee405bee1ede2df0b49
Author: Kjell Ahlstedt <kjell ahlstedt bredband net>
Date:   Thu Sep 1 09:06:30 2016 +0200

    Glib::OptionGroup: Improve the documentation of add_entry()

 glib/src/optiongroup.hg |   22 +++++++++++++++-------
 1 files changed, 15 insertions(+), 7 deletions(-)
---
diff --git a/glib/src/optiongroup.hg b/glib/src/optiongroup.hg
index 9995d5f..e89f27c 100644
--- a/glib/src/optiongroup.hg
+++ b/glib/src/optiongroup.hg
@@ -89,25 +89,26 @@ public:
   using vecstrings = std::vector<std::string>;
 
   /** Add a boolean option @a entry.
-   * The @arg parameter will be set to the option's extra argument
-   * after OptionContext::parse() has returned.
+   * If the option exists among the parsed arguments, the @a arg parameter will
+   * be set to <tt>true</tt> or, if @a entry contains OptionEntry::FLAG_REVERSE,
+   * to <tt>false</tt> after OptionContext::parse() has returned.
    */
   void add_entry(const OptionEntry& entry, bool& arg);
 
   /** Add an integer option @a entry.
-   * The @arg parameter will be set to the option's extra argument
+   * The @a arg parameter will be set to the option's extra argument
    * after OptionContext::parse() has returned.
    */
   void add_entry(const OptionEntry& entry, int& arg);
 
   /** Add a double option @a entry.
-   * The @arg parameter will be set to the option's extra argument
+   * The @a arg parameter will be set to the option's extra argument
    * after OptionContext::parse() has returned.
    */
   void add_entry(const OptionEntry& entry, double& arg);
 
   /** Add a UTF-8 string option @a entry.
-   * The @arg parameter will be set to the option's extra argument
+   * The @a arg parameter will be set to the option's extra argument
    * after OptionContext::parse() has returned.
    *
    * As indicated by the Glib::ustring type, the string will be
@@ -116,7 +117,7 @@ public:
   void add_entry(const OptionEntry& entry, Glib::ustring& arg);
 
   /** Add a filename string option @a entry.
-   * The @arg parameter will be set to the option's extra argument
+   * The @a arg parameter will be set to the option's extra argument
    * after OptionContext::parse() has returned.
    *
    * The string will be in glib's filename encoding.
@@ -124,13 +125,20 @@ public:
   void add_entry_filename(const OptionEntry& entry, std::string& arg);
 
   /** Add an option @a entry that provides a list of UTF-8 strings.
-   * The @arg parameter will be set to the option's extra argument
+   * The @a arg parameter will be set to the option's extra argument
    * after OptionContext::parse() has returned.
    *
    * As indicated by the Glib::ustring type, the strings will be
    * UTF-8 encoded.
    */
   void add_entry(const OptionEntry& entry, vecustrings& arg);
+
+  /** Add an option @a entry that provides a list of filename strings.
+   * The @a arg parameter will be set to the option's extra argument
+   * after OptionContext::parse() has returned.
+   *
+   * The strings will be in glib's filename encoding.
+   */
   void add_entry_filename(const OptionEntry& entry, vecstrings& arg);
 
   /** Add a string option @a entry, but let a callback slot parse the extra argument