website: use https URLs instead of http URLs in download page

Also add markdown formatting for decNumber URL so it gets rendered as a
link in the html page.

docs/content/download/default.yml

@@ -13,14 +13,14 @@ body:
  details, read the file `COPYING` in the source distribution.
 
  jq uses a C library for decimal number support. This is an ICU 1.8.1
- licensed code obtained from the ICU downloads archive
- http://download.icu-project.org/files/decNumber/decNumber-icu-368.zip.
+ licensed code obtained from the ICU downloads archive. 
+ <https://download.icu-project.org/files/decNumber/decNumber-icu-368.zip>
 
 
  ### Linux
 
  * jq is in the official [Debian](https://packages.debian.org/jq) and
- [Ubuntu](http://packages.ubuntu.com/jq) repositories. Install using
+ [Ubuntu](https://packages.ubuntu.com/jq) repositories. Install using
  `sudo apt-get install jq`.
 
  * jq is in the official [Fedora](https://src.fedoraproject.org/rpms/jq) repository.
@@ -61,7 +61,7 @@ body:
 
  ### macOS
 
- * Use [Homebrew](http://brew.sh/) to install jq with `brew install jq`.
+ * Use [Homebrew](https://brew.sh/) to install jq with `brew install jq`.
 
  * Use [MacPorts](https://www.macports.org) to install jq with `port install jq`.
 
@@ -199,7 +199,7 @@ body:
  On macOS, these are all included in Apple's command line tools, which can
  be installed from [Xcode](https://developer.apple.com/xcode/). However,
  you may find that you need a newer version of Bison than the one provided
- by Apple. This can be found in [Homebrew](http://brew.sh) or
+ by Apple. This can be found in [Homebrew](https://brew.sh/) or
  [MacPorts](https://macports.org/).
 
  If you want to generate the lexer and parser from source you can use the