[doc] fix git add argument

error: unknown switch `a'
usage: git add [<options>] [--] <pathspec>...

    -n, --dry-run         dry run
    -v, --verbose         be verbose

    -i, --interactive     interactive picking
    -p, --patch           select hunks interactively
    -e, --edit            edit current diff and apply
    -f, --force           allow adding otherwise ignored files
    -u, --update          update tracked files
    --renormalize         renormalize EOL of tracked files (implies -u)
    -N, --intent-to-add   record only the fact that the path will be added later
    -A, --all             add changes from all tracked and untracked files
    --ignore-removal      ignore paths removed in the working tree (same as --no-all)
    --refresh             don't add, only refresh the index
    --ignore-errors       just skip files which cannot be added because of errors
    --ignore-missing      check if - even missing - files are ignored in dry run
    --chmod (+|-)x        override the executable bit of the listed files

doc/release-process.md

@@ -219,7 +219,7 @@ Codesigner only: Commit the detached codesign payloads:
     rm -rf *
     tar xf signature-osx.tar.gz
     tar xf signature-win.tar.gz
-    git add -a
+    git add -A
     git commit -m "point to ${VERSION}"
     git tag -s v${VERSION} HEAD
     git push the current branch and new tag