Update url to target attribute documentation (#366)

The link was pointing to an unmaintained documentation page that
happened to be indexed by search engines in preference to the actual
documentation.

---
name: Update url to target attribute documentation
about: Technical issues, document format problems, bugs in scripts or
feature proposal.

---

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main/acle.md

@@ -423,6 +423,7 @@ Armv8.4-A [[ARMARMv84]](#ARMARMv84). Support is added for the Dot Product intrin
 * Fixed range of operand `o0` (too small) in AArch64 system register designations.
 * Fixed SVE2.1 quadword gather load/scatter store intrinsics.
 * Removed unnecessary Zd argument from `svcvtnb_mf8[_f32_x2]_fpm`.
+* Fixed urls.
 
 ### References
 
@@ -2584,7 +2585,7 @@ be found in [[BA]](#BA).
 
 This section describes ACLE features that use GNU-style attributes.
 The general rules for attribute syntax are described in the GCC
-documentation <https://gcc.gnu.org/onlinedocs/gcc/extensions-to-the-c-language-family/attribute-syntax.html>.
+documentation <https://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html>.
 Briefly, for this declaration:
 
 ``` c

main/design_documents/function-multi-versioning.md

@@ -25,7 +25,7 @@ derived from a function via FMV:
 2. the derived function obey to the same calling convention of the original
 function.
 
-Currently the `target` [attribute for aarch64](https://gcc.gnu.org/onlinedocs/gcc/extensions-to-the-c-language-family/declaring-attributes-of-functions/aarch64-function-attributes.html)
+Currently the `target` [attribute for aarch64](https://gcc.gnu.org/onlinedocs/gcc/AArch64-Function-Attributes.html)
 is used for many purposes, some of which might overlap the functionality
 introduced by FMV. To avoid confusion, we named the attributes used by FMV with
 `target_version` and `target_clones`.