[sr-dev] [kamailio/kamailio] Minor doc changes to Registrar module (#2477)

### Description Use of acronym "HF" (header field) in the REGISTRAR is a bit obscure. It probably makes sense to experienced Kamailio admins, but it's not immediately apparent to beginners. Since there is little gained by using the acronym in this document it would be more friendly to use "header field". Also, there is a double negative in section 4.1/flags/0x01: ``` 0x01 - save the contacts only in memory cache without no DB operation; ``` The literal meaning of this sentence is that it performs a DB operation. This should be changed to "with no" or possibly just "without", or even "with no". ### Expected behavior Use 'header field' instead of 'HF'. Use "with" instead of "without no". #### Actual observed behavior As indicated above #### Debugging Data Not applicable #### Log Messages Not applicable #### SIP Traffic Not applicable ### Possible Solutions Use 'header field' instead of 'HF'. Use "with" instead of "without no". ### Additional Information * **Kamailio Version** - output of `kamailio -v` Exists in most recent code branch. * **Operating System**: Not applicable. -- You are receiving this because you are subscribed to this thread. Reply to this email directly or view it on GitHub: https://github.com/kamailio/kamailio/issues/2477