[gtksourceview] docs: remove revision dates, git is better at providing that info

[Sébastien Wilmet <swilmet src gnome org>]

commit 0cef4004dd25b055292b8b64e9c9baaa8dd289b3
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Sun Sep 17 16:55:42 2017 +0200

    docs: remove revision dates, git is better at providing that info
    
    Most of the time we forget to update those dates. A wrong date is worse
    than no dates at all.

 docs/reference/lang-reference.xml.in  |    2 +-
 docs/reference/lang-tutorial.xml      |    2 +-
 docs/reference/style-reference.xml.in |    2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/docs/reference/lang-reference.xml.in b/docs/reference/lang-reference.xml.in
index a89bf27..e4e48a9 100644
--- a/docs/reference/lang-reference.xml.in
+++ b/docs/reference/lang-reference.xml.in
@@ -6,7 +6,7 @@
  <!ENTITY % gtkdocentities SYSTEM "xml/gtkdocentities.ent">
  %gtkdocentities;
 ]>
-<refentry id="lang-reference" revision="6 March 2015">
+<refentry id="lang-reference">
 <refmeta>
 <refentrytitle>Language Definition v2.0 Reference</refentrytitle>
 </refmeta>
diff --git a/docs/reference/lang-tutorial.xml b/docs/reference/lang-tutorial.xml
index 7766e27..ad9b58d 100644
--- a/docs/reference/lang-tutorial.xml
+++ b/docs/reference/lang-tutorial.xml
@@ -6,7 +6,7 @@
  <!ENTITY % gtkdocentities SYSTEM "xml/gtkdocentities.ent">
  %gtkdocentities;
 ]>
-<refentry id="lang-tutorial" revision="5 May 2005">
+<refentry id="lang-tutorial">
 <refmeta>
 <refentrytitle>Language Definition v2.0 Tutorial</refentrytitle>
 </refmeta>
diff --git a/docs/reference/style-reference.xml.in b/docs/reference/style-reference.xml.in
index fe8b081..dcf2976 100644
--- a/docs/reference/style-reference.xml.in
+++ b/docs/reference/style-reference.xml.in
@@ -6,7 +6,7 @@
  <!ENTITY % gtkdocentities SYSTEM "xml/gtkdocentities.ent">
  %gtkdocentities;
 ]>
-<refentry id="style-reference" revision="6 October 2013">
+<refentry id="style-reference">
 <refmeta>
 <refentrytitle>Style Scheme Definition Reference</refentrytitle>
 </refmeta>