Prepare for v1.1.8 release: Update DESCRIPTION and NEWS.md (#610)

Co-authored-by: Zhao <zhayuji4@merck.com>

Author: LittleBeannie

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: gsDesign2
 Title: Group Sequential Design with Non-Constant Effect
-Version: 1.1.7
+Version: 1.1.8
 Authors@R: c(
     person("Keaven", "Anderson", email = "keaven_anderson@merck.com", role = c("aut")),
     person("Yujie", "Zhao", email = "yujie.zhao@merck.com", role = c("aut", "cre")),

NEWS.md

@@ -1,3 +1,18 @@
+# gsDesign2 1.1.8
+
+## New features
+
+- The `gs_design_ahr()` function has been updated to allow outputting spending time (#602, thanks to @LittleBeannie).
+
+## Documentation
+
+- Documentation has been migrated to roxygen2 7.3.3 for improved maintainability and consistency (#601, thanks to @jdblischak).
+- An example demonstrating how to update a stratified design at the time of analysis has been added to the `gs_update_ahr()` function documentation (#608, thanks to @LittleBeannie).
+
+## Testing
+
+- Additional developer tests of `gs_design_ahr()` have been added (#604, thanks to @LittleBeannie).
+
 # gsDesign2 1.1.7
 
 ## Documentation