doc: fix spelling about ReStructured Text

- ReStructured Text should be exactly reStructuredText
- "reStructuredText" is ONE word, not two! according to https://docutils.sourceforge.io/rst.html

Signed-off-by: Maki Hatano <Maki.Y.Hatano@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240323062141.14863-1-Maki.Y.Hatano@gmail.com

Author: Maki Hatano

Documentation/doc-guide/parse-headers.rst

@@ -61,7 +61,7 @@ DESCRIPTION
 ***********
 
 
-Convert a C header or source file (C_FILE), into a ReStructured Text
+Convert a C header or source file (C_FILE), into a reStructuredText
 included via ..parsed-literal block with cross-references for the
 documentation files that describe the API. It accepts an optional
 EXCEPTIONS_FILE with describes what elements will be either ignored or

Documentation/index.rst

@@ -107,7 +107,7 @@ Other documentation
 
 There are several unsorted documents that don't seem to fit on other parts
 of the documentation body, or may require some adjustments and/or conversion
-to ReStructured Text format, or are simply too old.
+to reStructuredText format, or are simply too old.
 
 .. toctree::
    :maxdepth: 1

Documentation/translations/it_IT/index.rst

@@ -132,4 +132,4 @@ Documentazione varia
 
 Ci sono documenti che sono difficili da inserire nell'attuale organizzazione
 della documentazione; altri hanno bisogno di essere migliorati e/o convertiti
-nel formato *ReStructured Text*; altri sono semplicamente troppo vecchi.
+nel formato *reStructuredText*; altri sono semplicamente troppo vecchi.