fix: broken links in the docs fixed

docs/users_guide/framework_basics/concepts.md

@@ -95,7 +95,7 @@ and when `T` is implicitly convertible to `V`.
 and is satisfied by:
 
 - All units derived from a `named_unit` class template instantiated with a unique symbol identifier
-  and a [`QuantitySpec`](#quantityspec) of a [quantity kind](../../appendix/glossary.md#kind).
+  and a [`QuantitySpec`](#QuantitySpec) of a [quantity kind](../../appendix/glossary.md#kind).
 - All units being a result of [unit equations](../../appendix/glossary.md#unit-equation) on other
   associated units.
 

docs/users_guide/framework_basics/text_output.md

@@ -241,7 +241,7 @@ static_assert(unit_symbol<{.solidus = unit_symbol_solidus::never,
 
     `std::string_view` is returned only when C++23 is available. Otherwise, an instance of a
     `basic_fixed_string` is being returned. See more in the
-    [C++ compiler support](../../getting_started/installation_and_usage.md#static-constexpr-variables-in-constexpr-functions)
+    [C++ compiler support](../../getting_started/cpp_compiler_support.md#static-constexpr-variables-in-constexpr-functions)
     chapter.
 
 #### `unit_symbol_to()`

docs/users_guide/framework_basics/the_affine_space.md

@@ -219,7 +219,7 @@ the origin and the _displacement vector_ measured from it to the point we create
     [Why can't I create a quantity by passing a number to a constructor?](../../getting_started/faq.md#why-cant-i-create-a-quantity-by-passing-a-number-to-a-constructor)
     chapter.
 
-Similarly to [creation of a quantity](../../getting_started/quick_start.md#creating-a-quantity),
+Similarly to [creation of a quantity](../../getting_started/quick_start.md#quantities),
 if someone does not like the operator-based syntax to create a `quantity_point`, the same results
 can be achieved with a two-parameter constructor: