fix: correct typos in code comments, docstrings and docs (#13931)

## Summary
- Fix `a image` → `an image` in README and log message
- Fix `colomn` → `column` in table structure recognizer comment
- Fix `formated` → `formatted` in confluence connector docstring
- Fix `tabel of content` → `table of contents` in TOC prompt

## Test plan
- [ ] Documentation and comment changes, no functional impact

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: yuj <yuj@ztjzsoft.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: Jin Hai <haijin.chn@gmail.com>

deepdoc/parser/pdf_parser.py

@@ -708,7 +708,7 @@ class RAGFlowPdfParser:
     def __ocr(self, pagenum, img, chars, ZM=3, device_id: int | None = None):
         start = timer()
         bxs = self.ocr.detect(np.array(img), device_id)
-        logging.info(f"__ocr detecting boxes of a image cost ({timer() - start}s)")
+        logging.info(f"__ocr detecting boxes of an image cost ({timer() - start}s)")
 
         start = timer()
         if not bxs: