Explain ":foo" parsing mode in Core notes

docs/Core.rst

@@ -340,12 +340,22 @@ This section is for odd but important notes that don't fit anywhere else.
   that's preserved between different runs of DF (use up/down keys to go through
   the history).
 
-* To include whitespace in the argument/s to some command, quote it in
-  double quotes.  To include a double quote character, use ``\"``.
-
 * The binaries for 0.40.15-r1 to 0.34.11-r4 are on DFFD_.
   Older versions are available here_.
 
   .. _DFFD: http://dffd.bay12games.com/search.php?string=DFHack&id=15&limit=1000
   .. _here: http://dethware.org/dfhack/download
 
+* To include whitespace in the argument/s to some command, quote it in
+  double quotes.  To include a double quote character, use ``\"``.
+
+* If the first non-whitespace character is ``:``, the command is parsed in
+  an alternative mode which is very useful for the `lua` and `rb_eval` commands.
+  The following two command lines are exactly equivalent::
+
+    :foo a b "c d" e f
+    foo "a b \"c d\" e f"
+
+  * non-whitespace characters following the ``:`` are the command name
+  * the remaining part of the line is used verbatim as the first argument
+

docs/Plugins.rst

@@ -393,17 +393,7 @@ keybinding is :kbd:`Ctrl`:kbd:`F1`.  See also `hotkey-notes`.
 rb_eval
 -------
 Evaluate the following arguments as a ruby string.  Best used as
-``:rb_eval [string]``, for the special parsing mode:
-
-If the first non-whitespace character is ``:``, the command is parsed in a special
-alternative mode: first, non-whitespace characters immediately following the ``:``
-are used as the command name; the remaining part of the line, starting with the first
-non-whitespace character *after* the command name, is used verbatim as the first argument.
-The following two command lines are exactly equivalent::
-
-    :foo a b "c d" e f
-    foo "a b \"c d\" e f"
-
+``:rb_eval [string]``, for the special parsing mode.
 
 .. _manipulator: