[DOC] Use https where possible

.github/ISSUE_TEMPLATE/release-checklist.md

@@ -8,7 +8,7 @@ assignees: ''
 ---
 
 - [ ] Check for critical performance regressions.
-- [ ] Check [Nightlies](http://cdash.seqan.de/index.php?project=SeqAn3) for critical build failures.
+- [ ] Check [Nightlies](https://cdash.seqan.de/index.php?project=SeqAn3) for critical build failures.
 - [ ] Check the [Changelog.md](https://github.com/seqan/seqan3/blob/master/CHANGELOG.md) for completeness.
 - [ ] Update the index from cppreference.com so that up-to-date documentation links are generated.
   <details><summary>Click for detailed steps</summary><br>

CHANGELOG.md

@@ -5,11 +5,11 @@
 This changelog contains a top-level entry for each release with sections on new features, API changes and notable
 bug-fixes (not all bug-fixes will be listed).
 
-Get to know SeqAn3 with our [tutorials](http://docs.seqan.de/seqan/3-master-user/usergroup1.html).
+Get to know SeqAn3 with our [tutorials](https://docs.seqan.de/seqan/3-master-user/usergroup1.html).
 
 Please see the release announcement: https://www.seqan.de/announcing-seqan3/
 
-See the porting guide for some help on porting: http://docs.seqan.de/seqan/3-master-user/howto_porting.html
+See the porting guide for some help on porting: https://docs.seqan.de/seqan/3-master-user/howto_porting.html
 
 See the documentation on [API stability](https://docs.seqan.de/seqan/3-master-user/about_api.html) to learn about
 when API changes are allowed.
@@ -294,7 +294,7 @@ Note that 3.1.0 will be the first API stable release and interfaces in this rele
   ([\#1471](https://github.com/seqan/seqan3/pull/1471)).
 * Customising for third party types has changes slightly:
   You are only affected if you added types to `seqan3::custom::`.
-  Please see [About Customisation](http://docs.seqan.de/seqan/3.0.1/about_customisation.html)
+  Please see [About Customisation](https://docs.seqan.de/seqan/3.0.1/about_customisation.html)
   ([\#1225](https://github.com/seqan/seqan3/pull/1225)).
 * All our concepts are named in the `snake_case` style
   (e.g. `seqan3::WritableAlphabet` -> `seqan3::writable_alphabet`)! This change was motivated by the decision of the

doc/main_page.md

@@ -28,7 +28,7 @@ Resources outside of this web-site that might be useful:
 
 ### Some notes on using this documentation
 
-We use [doxygen](http://doxygen.nl) to generate our documentation.
+We use [doxygen](https://doxygen.nl) to generate our documentation.
 It may not be the most beautiful system, but it works quite well in practice.
 If you spot any dead links in the documentation, please open an issue at our bug-tracker (see above) or
 [directly submit a pull request](\ref about_contributing) fixing the problem.

doc/tutorial/concepts/index.md

@@ -9,7 +9,7 @@ You will learn the terminology used in the context of concepts and how to use Se
 
 This tutorial teaches the very basics of working with concepts. For more background and information on how to implement
 your own concepts, we recommend:
-  * A well-readable [paper](http://www.stroustrup.com/good_concepts.pdf) with motivation and historical background.
+  * A well-readable [paper](https://www.stroustrup.com/good_concepts.pdf) with motivation and historical background.
   * The (rather dense) [documentation on cppreference](https://en.cppreference.com/w/cpp/language/constraints).
 
 # Constraints

doc/tutorial/ranges/index.md

@@ -287,7 +287,7 @@ On Linux based systems use `/usr/bin/time -v <program> <args>` and look for "Max
 On macOS and BSD use `/usr/bin/time -l <program> <args>` and look for "maximum resident set size".
 
 \note This command diplays the peak memory usage and only gives you a first impression. You can use [valgrind]
-(http://valgrind.org/docs/manual/ms-manual.html) if you want to have a more detailed analysis of your memory
+(https://valgrind.org/docs/manual/ms-manual.html) if you want to have a more detailed analysis of your memory
 consumption.
 \endassignment
 \solution

include/seqan3/range/container/concept.hpp

@@ -198,7 +198,7 @@ SEQAN3_CONCEPT sequence_container = requires (type val, type val2, type const cv
  * \brief A more refined container concept than seqan3::sequence_container.
  *
  * Adds requirements for `.at()`, `.resize()` and the subscript operator `[]`. Models the subset of the
- * [STL SequenceConcept](httpa://en.cppreference.com/w/cpp/concept/SequenceConcept) that is supported
+ * [STL SequenceConcept](https://en.cppreference.com/w/cpp/concept/SequenceConcept) that is supported
  * by `std::vector`, `std::deque` and `std::basic_string`.
  *
  * \attention