Merge pull request #2387 from graham-at-target/add-ids-to-important-sections

docs: Add IDs to important sections

doc/manual/advanced-topics/advanced-topics.xml

@@ -1,6 +1,7 @@
 <part xmlns="http://docbook.org/ns/docbook"
       xmlns:xlink="http://www.w3.org/1999/xlink"
       xmlns:xi="http://www.w3.org/2001/XInclude"
+      xml:id="part-advanced-topics"
       version="5.0">
 
 <title>Advanced Topics</title>

doc/manual/expressions/language-constructs.xml

@@ -41,7 +41,7 @@ encountered</quote>).</para></footnote>.</para>
 </simplesect>
 
 
-<simplesect><title>Let-expressions</title>
+<simplesect xml:id="sect-let-expressions"><title>Let-expressions</title>
 
 <para>A let-expression allows you define local variables for an
 expression.  For instance,

doc/manual/glossary/glossary.xml

@@ -1,5 +1,6 @@
 <appendix xmlns="http://docbook.org/ns/docbook"
-          xmlns:xlink="http://www.w3.org/1999/xlink">
+          xmlns:xlink="http://www.w3.org/1999/xlink"
+          xml:id="part-glossary">
 
 <title>Glossary</title>
 

doc/manual/installation/env-variables.xml

@@ -55,7 +55,7 @@ export NIX_SSL_CERT_FILE=/etc/ssl/my-certificate-bundle.crt
 the Nix installer will detect the presense of Nix configuration, and
 abort.</para></note>
 
-<section>
+<section xml:id="sec-nix-ssl-cert-file-with-nix-daemon-and-macos">
 <title><envar>NIX_SSL_CERT_FILE</envar> with macOS and the Nix daemon</title>
 
 <para>On macOS you must specify the environment variable for the Nix