typo

docs/Developer-Guide_Build-Options.md

@@ -193,7 +193,7 @@ Example:
     - `CRYPTROOT_SSH_UNLOCK_PORT=2222` Default: `2022`
     - `CRYPTROOT_MAPPER=armbian-root` Default: `armbian-root`
     - **Note:** Cryptsetup root mapper name
-    - **Hint:** Can be helpfull for parallel image building
+    - **Hint:** Can be helpful for parallel image building
     - `CRYPTROOT_PARAMETERS="custom cryptsetup options"` Default: `--pbkdf pbkdf2` (May not contain `=`; separate with spaces)
     - **Note:** This function might not work well with all distributions. Debian Buster and Stretch were tested. For building under Docker, you have to use privileged mode, which can be enabled in `userpatches/config-docker`.
     - **Warning:** This feature was added as a community contribution and is mostly functional. Under some circumstances, though, the prompt will not be shown. Therefore, it should be considered experimental. Check [here](https://github.com/armbian/build/commit/681e58b6689acda6a957e325f12e7b748faa8330) and [here](https://github.com/armbian/build/issues/1183)