doc: assign ids to many headings

without stable ids on headings we cannot generate stable links to these
headings. nrd complains about this, but the current docbook workflow
does not.

a few generated ids remain, mostly in examples and footnotes. most of
the examples are generated by nixdoc (which has since gained MD export
functions, and the MD export does generate IDs).

1 files changed, 4 insertions, 4 deletions

diff --git a/doc/languages-frameworks/pkg-config.section.md b/doc/languages-frameworks/pkg-config.section.md
index fb6fee997d6f2..75cbdaeb6fe88 100644
--- a/doc/languages-frameworks/pkg-config.section.md
+++ b/doc/languages-frameworks/pkg-config.section.md
@@ -4,7 +4,7 @@
 
 Nixpkgs provides a couple of facilities for working with this tool.
 
-## Writing packages providing pkg-config modules
+## Writing packages providing pkg-config modules {#pkg-config-writing-packages}
 
 Packages should set `meta.pkgConfigModules` with the list of package config modules they provide.
 They should also use `testers.testMetaPkgConfig` to check that the final built package matches that list.
@@ -29,9 +29,9 @@ stdenv.mkDerivation (finalAttrs: {
 })
 ```
 
-## Accessing packages via pkg-config module name
+## Accessing packages via pkg-config module name {#sec-pkg-config-usage}
 
-### Within Nixpkgs
+### Within Nixpkgs {#sec-pkg-config-usage-internal}
 
 A [setup hook](#setup-hook-pkg-config) is bundled in the `pkg-config` package to bring a derivation's declared build inputs into the environment.
 This will populate environment variables like `PKG_CONFIG_PATH`, `PKG_CONFIG_PATH_FOR_BUILD`, and `PKG_CONFIG_PATH_HOST` based on:
@@ -44,7 +44,7 @@ For more details see the section on [specifying dependencies in general](#ssec-s
 
 Normal pkg-config commands to look up dependencies by name will then work with those environment variables defined by the hook.
 
-### Externally
+### Externally {#sec-pkg-config-usage-external}
 
 The `defaultPkgConfigPackages` package set is a set of aliases, named after the modules they provide.
 This is meant to be used by language-to-nix integrations.