chore: prepare for 6.0.0-b.1 release

Author: wincent

doc/command-t.txt

@@ -595,7 +595,7 @@ POSSIBILITY OF SUCH DAMAGE.
 
 HISTORY                                         *command-t-history*
 
-main (not yet released) ~
+6.0.0-b.1 (16 December 2022) ~
 
 - fix: actually respect `scanners.git.submodules` and `scanners.git.untracked`
   options in |commandt.setup()| (https://github.com/wincent/command-t/pull/414).

lua/wincent/commandt/version.lua

@@ -5,6 +5,6 @@ return {
   major = 6,
   minor = 0,
   patch = 0,
-  prerelease = 'b.0',
-  version = '6.0.0-b.0',
+  prerelease = 'b.1',
+  version = '6.0.0-b.1',
 }