add more documentation

pkgs/nu-git-manager-sugar/nu-git-manager-sugar/git/mod.nu

@@ -355,8 +355,26 @@ def throw-error [
     }
 }
 
+# bisect a worktree by running a piece of code repeatedly
+#
+# # Examples
+# ```nushell
+# # find a bug that was introduced in Nushell in `nushell/nushell
+# gm repo bisect --good 0.89.0 --bad 4458aae {
+#     cargo run -- -n -c "def foo [x: list<string>] { $x }; foo []"
+# }
+# ```
+# ```
+# 724818030dd1de392c54788eab5030074d694ecd
+# ```
+# ---
+# ```nushell
+# # avoid running the test twice more if it is expensive and you're sure
+# # `--good` and `--bad` are indeed "good" and "bad"
+# gm repo bisect --good $good --bad $bad --no-check $test
+# ```
 export def "gm repo bisect" [
-    test: closure, # the code to run to check a given revision
+    test: closure, # the code to run to check a given revision, should return a non-zero exit code for bad revisions
     --good: string, # the initial known "good" revision
     --bad: string, # the initial known "bad" revision
     --no-check, # don't check if `--good` and `--bad` are indeed "good" and "bad"