Merge branch 'es/git-debugger-doc' into maint

Doc update.

* es/git-debugger-doc:
  doc: hint about GIT_DEBUGGER in CodingGuidelines

Documentation/CodingGuidelines

@@ -412,6 +412,12 @@ For C programs:
    must be declared with "extern" in header files. However, function
    declarations should not use "extern", as that is already the default.
 
+ - You can launch gdb around your program using the shorthand GIT_DEBUGGER.
+   Run `GIT_DEBUGGER=1 ./bin-wrappers/git foo` to simply use gdb as is, or
+   run `GIT_DEBUGGER="<debugger> <debugger-args>" ./bin-wrappers/git foo` to
+   use your own debugger and arguments. Example: `GIT_DEBUGGER="ddd --gdb"
+   ./bin-wrappers/git log` (See `wrap-for-bin.sh`.)
+
 For Perl programs:
 
  - Most of the C guidelines above apply.