doc: Add anchors to long lists

Added using the following sed scripts:

- For command-ref/opt-common.md:

    s~- `(--?)([^`]+)`~- [`\1\2`]{#opt-\2}~g

- For expressions/builtin-constants.md:

    s~- `(builtins\.?)([^`]+)`~- [`\1\2`]{#builtins-\2}~g

- For expressions/advanced-attributes.md

    s~^  - `([^`]+)`~  - [`\1`]{#adv-attr-\1}~g

  and manually adjusted outputHashAlgo & outputHashMode.

- For glossary.md

    s~^  - (`([^`]+)`|(.+)) ?\\~  - [\1]{#gloss-\2\3}\\~g;
    s~(gloss-\w+) ~\1-~g

  and manually adjusted anchors for Nix expression, user environment, NAR, ∅ and ε.

- For command-ref/env-common.md

    s~^  - `([^`]+)`~  - [`\1`]{#env-\1}~g'

1 files changed, 1 insertions, 1 deletions

diff --git a/doc/manual/src/expressions/builtin-constants.md b/doc/manual/src/expressions/builtin-constants.md
index 1404289e5..78d066a82 100644
--- a/doc/manual/src/expressions/builtin-constants.md
+++ b/doc/manual/src/expressions/builtin-constants.md
@@ -14,7 +14,7 @@ Here are the constants built into the Nix expression evaluator:
     This allows a Nix expression to fall back gracefully on older Nix
     installations that don’t have the desired built-in function.
 
-  - `builtins.currentSystem`\
+  - [`builtins.currentSystem`]{#builtins-currentSystem}\
     The built-in value `currentSystem` evaluates to the Nix platform
     identifier for the Nix installation on which the expression is being
     evaluated, such as `"i686-linux"` or `"x86_64-darwin"`.