update user manual for future v2.6.0

Author: beaudu

DOC/user-manual/WebObs_Manual.tex

@@ -40,9 +40,9 @@
 \renewcommand*{\familydefault}{\sfdefault}
 
 % ------ local variables
-\newcommand{\release}{2.5.3}
-\newcommand{\releasename}{v2.5.3}
-\newcommand{\releasedate}{September, 2022}
+\newcommand{\release}{2.6.0}
+\newcommand{\releasename}{v2.6.0}
+\newcommand{\releasedate}{August, 2023}
 \newcommand{\webobs}{\textbf{WebObs }}
 \newcommand{\wo}[1]{\MakeTextUppercase{#1}}
 \newcommand{\wofile}[1]{\small{\textbf{#1}}}