[tellico] doc: doc: Write docbook date in standard format

[Alexander Potashev]

Git commit 35c44b6d7f6a410906462818395ea54b202c115d by Alexander Potashev.
Committed on 12/06/2019 at 21:09.
Pushed by aspotashev into branch 'master'.

doc: Write docbook date in standard format

Import comments from https://cgit.kde.org/kdoctools.git/tree/src/template.docbook

M  +18   -7    doc/index.docbook

https://commits.kde.org/tellico/35c44b6d7f6a410906462818395ea54b202c115d

diff --git a/doc/index.docbook b/doc/index.docbook
index 73446352..6f29d0ae 100644
--- a/doc/index.docbook
+++ b/doc/index.docbook
@@ -33,13 +33,24 @@ as Authors, publish date, the abstract, and Keywords -->
 
 <bookinfo>
 
-<!-- Date and version information of the documentation
-Don't forget to include this last date and this last revision number, we
-need them for translation coordination !
-Please respect the format of the date (DD/MM/YYYY) and of the version
-(V.MM.LL), it could be used by automation scripts.
-Do NOT change these in the translation. -->
-<date>12/05/2019</date>
+<!-- Date of the documentation
+Change date/releaseinfo only if
+   docbook is updated and verified to be valid for the current app version
+   or
+   docbook is proofread and verified to be valid for the current app version
+Don't forget to include this last date.
+Please respect the format of the date (YYYY-MM-DD),it is used by scripts.
+-->
+<date>2019/05/12</date>
+
+<!--version information of Frameworks/Plasma/Applications this documentation is valid for.
+Example:
+Frameworks xx.yy for docbooks in frameworks
+Plasma xx.yy for docbooks in plasma workspace
+Applications xx.yy for docbooks released as Applications
+xx.yy (Applications xx.yy) for docbooks with own version released as Applications
+$applicationname xx.yy for applications with independent release schedule (extragear/playground)
+-->
 <releaseinfo>3.2</releaseinfo>
 
 <title>The &tellico; Handbook</title>