doc: Fix description of some GUCs in docs and postgresql.conf.sample

The following parameters have been imprecise, or incorrect, about their
description (PGC_POSTMASTER or PGC_SIGHUP):
- autovacuum_work_mem (docs, as of 9.6~)
- huge_page_size (docs, as of 14~)
- max_logical_replication_workers (docs, as of 10~)
- max_sync_workers_per_subscription (docs, as of 10~)
- min_dynamic_shared_memory (docs, as of 14~)
- recovery_init_sync_method (postgresql.conf.sample, as of 14~)
- remove_temp_files_after_crash (docs, as of 14~)
- restart_after_crash (docs, as of 9.6~)
- ssl_min_protocol_version (docs, as of 12~)
- ssl_max_protocol_version (docs, as of 12~)

This commit adjusts the description of all these parameters to be more
consistent with the practice used for the others.

Revewed-by: Justin Pryzby
Discussion: https://postgr.es/m/YK2ltuLpe+FbRXzA@paquier.xyz
Backpatch-through: 9.6

doc/src/sgml/config.sgml

@@ -1472,6 +1472,11 @@ include_dir 'conf.d'
         The default is <literal>TLSv1.2</literal>, which satisfies industry
         best practices as of this writing.
        </para>
+
+       <para>
+        This parameter can only be set in the <filename>postgresql.conf</filename>
+        file or on the server command line.
+       </para>
       </listitem>
      </varlistentry>
 
@@ -1490,6 +1495,11 @@ include_dir 'conf.d'
         useful for testing or if some component has issues working with a
         newer protocol.
        </para>
+
+       <para>
+        This parameter can only be set in the <filename>postgresql.conf</filename>
+        file or on the server command line.
+       </para>
       </listitem>
      </varlistentry>
 
@@ -1703,7 +1713,7 @@ include_dir 'conf.d'
         <xref linkend="guc-huge-pages"/>.
         The default is zero (<literal>0</literal>).
         When set to <literal>0</literal>, the default huge page size on the
-        system will be used.
+        system will be used. This parameter can only be set at server start.
        </para>
        <para>
         Some commonly available page sizes on modern 64 bit server architectures include:
@@ -1900,6 +1910,9 @@ include_dir 'conf.d'
         the value of <xref linkend="guc-maintenance-work-mem"/> should
         be used instead.  The setting has no effect on the behavior of
         <command>VACUUM</command> when run in other contexts.
+        This parameter can only be set in the
+        <filename>postgresql.conf</filename> file or on the server command
+        line.
        </para>
       </listitem>
      </varlistentry>
@@ -2029,7 +2042,8 @@ include_dir 'conf.d'
         the <varname>huge_pages</varname> setting on operating systems where
         that is supported, and may be more likely to benefit from larger pages
         on operating systems where that is managed automatically.
-        The default value is <literal>0</literal> (none).
+        The default value is <literal>0</literal> (none). This parameter can
+        only be set at server start.
        </para>
       </listitem>
      </varlistentry>
@@ -4794,7 +4808,8 @@ ANY <replaceable class="parameter">num_sync</replaceable> ( <replaceable class="
         <varname>max_worker_processes</varname>.
        </para>
        <para>
-        The default value is 4.
+        The default value is 4. This parameter can only be set at server
+        start.
        </para>
       </listitem>
      </varlistentry>
@@ -4819,7 +4834,9 @@ ANY <replaceable class="parameter">num_sync</replaceable> ( <replaceable class="
         <varname>max_logical_replication_workers</varname>.
        </para>
        <para>
-        The default value is 2.
+        The default value is 2. This parameter can only be set in the
+        <filename>postgresql.conf</filename> file or on the server command
+        line.
        </para>
       </listitem>
      </varlistentry>
@@ -9836,6 +9853,11 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
         useful to disable the restart so that the clusterware can gain
         control and take any actions it deems appropriate.
        </para>
+
+       <para>
+        This parameter can only be set in the <filename>postgresql.conf</filename>
+        file or on the server command line.
+       </para>
       </listitem>
      </varlistentry>
 
@@ -9853,6 +9875,11 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
         retained and may be used for debugging, for example. Repeated crashes
         may however result in accumulation of useless files.
        </para>
+
+       <para>
+        This parameter can only be set in the <filename>postgresql.conf</filename>
+        file or on the server command line.
+       </para>
       </listitem>
      </varlistentry>
 
@@ -9921,6 +9948,9 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
         <productname>PostgreSQL</productname>, and relevant error messages may
         appear only in kernel logs.
        </para>
+       <para>
+        This parameter can only be set at server start.
+       </para>
       </listitem>
      </varlistentry>
 

src/backend/utils/misc/postgresql.conf.sample

@@ -774,6 +774,7 @@
 					# data?
 					# (change requires restart)
 #recovery_init_sync_method = fsync	# fsync, syncfs (Linux 5.8+)
+					# (change requires restart)
 
 
 #------------------------------------------------------------------------------