auth_db docs: Eliminate references to "HA1b"; Document new columns

Credits to Adrian Georgescu for the report!

modules/auth_db/doc/auth_db_admin.xml

@@ -90,36 +90,38 @@ modparam("auth_db", "db_url", "&exampledb;")
 			<listitem><para><emphasis>1 (calculate HA1)</emphasis> - the loaded
 			password is a plaintext password, so OpenSIPS will internally
 			calculate the HA1. As the passwords will be loaded from the column
-			specified in the <quote>password_column</quote> parameter, be sure
-			this parameter points to a column holding a plaintext password
-			(by default, this parameter points to <quote>ha1</quote> column);
+			specified in the <xref linkend="param_password_column"/> parameter,
+			be sure this parameter points to a column holding a plaintext password
+			(by default, this parameter points to the <quote>ha1</quote> column);
 			</para></listitem>
-			<listitem><para><emphasis>0 (do NOT calculate HA1)</emphasis> - the
-			loaded password is an already computed HA1 value, so OpenSIPS does
-			not have do any further computing (for HA1 value). Depending on
-			the presence of a <quote>@domain</quote> part (some user agents
-			append the domain to the username credentials parameter too),
-			the modules will load the password (pre-computed HA1) from the
-			<quote>password_column_2</quote> column (if domain present) or from
-			the <quote>password_column</quote> column (if domain not present).
-			Usually, most of the UAs do NOT include a domain part in the
-			username credentials parameter.
+
+			<listitem><para><emphasis>0 (do <emphasis role='bold'>not</emphasis>
+			calculate HA1)</emphasis> - the loaded password is a pre-computed
+			HA1 hash (no calculation needed).  The module will load all hashes
+			stored in the <xref linkend="param_password_column"/>,
+			<xref linkend="param_hash_column_sha256"/> and
+			<xref linkend="param_hash_column_sha512t256"/> columns, then use
+			the hash corresponding to the hashing algorithm selected for a
+			given digest authentication challenge.
+			</para>
+
+			<para>
+			The content of the hash columns can be generated as follows:
+			<itemizedlist>
+			<listitem><para>password_column: MD5(username:realm:password)
 			</para></listitem>
+			<listitem><para>hash_column_sha256: SHA-256(username:realm:password)
+			</para></listitem>
+			<listitem><para>hash_column_sha512t256: SHA-512-256(username:realm:password)
+			</para></listitem>
+			</itemizedlist>
+			</para>
+
+			</listitem>
 		</itemizedlist>
 		<para>
-		The <quote>password_column_2</quote> column contains also HA1 strings
-		but they should be calculated including the domain in the username
-		parameter (as opposed to password_column which (when containing HA1
-		strings) should always contain HA1 strings calculated without domain
-		in username.
-		</para>
-		<para>
-		This ensures that the authentication will always work when using
-		pre-calculated HA1 strings, not depending on the presence of the
-		domain in username.
-		</para>
-		<para>
-		Default value of this parameter is 0.
+			Default value of this parameter is
+			<emphasis>0 (use hashed passwords)</emphasis>.
 		</para>
 		<example>
 		<title><varname>calculate_ha1</varname> parameter usage</title>
@@ -249,7 +251,7 @@ modparam("auth_db", "domain_column", "domain")
 		This is the name of the column in a 'SUBSCRIBER' like table holding
 		the passwords. Passwords can be
 		either stored as plain text or pre-calculated HA1 strings. HA1 strings
-		are MD5 hashes of username, password, and realm. HA1 strings are more
+		are MD5 hashes of username, password and realm. HA1 strings are more
 		safe because the server doesn't need to know plaintext passwords and
 		they cannot be obtained from HA1 strings.
 		</para>
@@ -264,6 +266,41 @@ modparam("auth_db", "password_column", "password")
 		</example>
 	</section>
 
+	<section id="param_hash_column_sha256" xreflabel="hash_column_sha256">
+		<title><varname>hash_column_sha256</varname> (string)</title>
+		<para>
+		The name of the column holding SHA-256 HA1 hashes
+		(<ulink url="https://datatracker.ietf.org/doc/html/rfc8760">RFC 8760</ulink> support).
+
+		</para>
+		<para>
+		Default value is <quote>ha1_sha256</quote>.
+		</para>
+		<example>
+		<title><varname>password_column</varname> parameter usage</title>
+		<programlisting format="linespecific">
+modparam("auth_db", "hash_column_sha256", "ha1_sha256")
+</programlisting>
+		</example>
+	</section>
+
+	<section id="param_hash_column_sha512t256" xreflabel="hash_column_sha512t256">
+		<title><varname>hash_column_sha512t256</varname> (string)</title>
+		<para>
+		The name of the column holding SHA-512/256 HA1 hashes.
+		(<ulink url="https://datatracker.ietf.org/doc/html/rfc8760">RFC 8760</ulink> support).
+		</para>
+		<para>
+		Default value is <quote>ha1_sha512t256</quote>.
+		</para>
+		<example>
+		<title><varname>password_column</varname> parameter usage</title>
+		<programlisting format="linespecific">
+modparam("auth_db", "hash_column_sha512t256", "ha1_sha512t256")
+</programlisting>
+		</example>
+	</section>
+
 	<section id="param_uri_user_column" xreflabel="uri_user_column">
 		<title><varname>uri_user_column</varname> (string)</title>
 		<para>