Add some missing unstable book tracking issue links

src/doc/unstable-book/src/compiler-flags/branch-protection.md

@@ -1,5 +1,9 @@
 # `branch-protection`
 
+The tracking issue for this feature is: [#113369](https://github.com/rust-lang/rust/issues/113369).
+
+------------------------
+
 This option lets you enable branch authentication instructions on AArch64.
 This option is only accepted when targeting AArch64 architectures.
 It takes some combination of the following values, separated by a `,`.

src/doc/unstable-book/src/language-features/more-qualified-paths.md

@@ -3,6 +3,10 @@
 The `more_qualified_paths` feature can be used in order to enable the
 use of qualified paths in patterns.
 
+The tracking issue for this feature is: [#86935](https://github.com/rust-lang/rust/issues/86935).
+
+------------------------
+
 ## Example
 
 ```rust

src/doc/unstable-book/src/language-features/postfix-match.md

@@ -3,6 +3,10 @@
 `postfix-match` adds the feature for matching upon values postfix
 the expressions that generate the values.
 
+The tracking issue for this feature is: [#121618](https://github.com/rust-lang/rust/issues/121618).
+
+------------------------
+
 ```rust,edition2021
 #![feature(postfix_match)]