pkg/micro-ecc: remove trailing whitespaces from doc.txt

pkg/micro-ecc/doc.txt

@@ -5,42 +5,42 @@
  * @brief    Micro-ECC for RIOT
  *
  * # Micro-ECC for RIOT
- * 
+ *
  * This port of Micro-ECC to RIOT is based on the Micro-ECC
  * [upstream](https://github.com/kmackay/micro-ecc) and adds `hwrng_read`
  * (provided by RIOT) as the default RNG function if it is available on the target
  * platform. This port also fixes a minor issue with unused variables in the
  * upstream code.
- * 
+ *
  * # Usage
- * 
+ *
  * ## Build
- * 
+ *
  * Add
  * ```Makefile
  * USEPKG += micro-ecc
  * ```
  * to your Makefile.
- * 
+ *
  * ## Choosing the right API
- * 
+ *
  * Before using the Micro-ECC library, you need to check the `Makefile.features`
  * of your target board to see if `periph_hwrng` is provided.
- * 
+ *
  * If it is provided, you may safely use `uECC_make_key` to generate ECDSA key
  * pairs and call `uECC_sign`/`uECC_verify` to sign/verify the ECDSA signatures.
- * 
+ *
  * If not, you cannot use `uECC_make_key` or `uECC_sign` APIs anymore. The ECDSA
  * keys have to be generated on a platform with HWRNG support (e.g., `native`) and
  * transferred to your target device. You need to use `uECC_sign_deterministic` to
  * perform ECDSA deterministic signing (standardized by RFC 6979). You can still
  * use `uECC_verify` to verify the signatures from both signing APIs.
- * 
+ *
  * **WARNING** Calling `uECC_make_key` and `uECC_sign` APIs on platforms without
  * HWRNG support will lead to compile failure.
- * 
+ *
  * Examples of using these uECC APIs can be found in the `test` folder of the
  * Micro-ECC upstream.
  *
  * @see     https://github.com/kmackay/micro-ecc
- */
+ */