Adding Liquid template language

**https://github.com/simpyll/awesome-liquid**

**The Shopify template language and static website preprocessor used by gh-pages, Jekyll, Shopify, and many more. It is _the_ most popular markup language on Github with well over four thousand stars. There are countless multifaceted, lengthy, and highly complex liquid scripts which blur the boundaries between static and dynamic websites. Liquid has hit the big time and is no longer some obscure language. It would be an honor to be a maintainer for this subsection on list awesome.**

- [x] I have read and understood the [contribution guidelines](https://github.com/sindresorhus/awesome/blob/master/contributing.md) and the [instructions for creating a list](https://github.com/sindresorhus/awesome/blob/master/create-list.md).
- [x] This pull request has a descriptive title. *(For example: `Add Node.js`)*
- [x] The list I added
- [x] **has been around for at least 20 days,**
- [x] is a non-generated Markdown file in a GitHub repo,
- [x] is not a duplicate,
- [x] only has awesome items with descriptions *(Awesome lists are curations of the best, not of everything)*,
- [x] contains the [awesome badge](https://github.com/sindresorhus/awesome/blob/master/awesome.md#awesome-badge) on the right side of the list heading,
- [x] has a Table of Contents section named `Contents` as the first section,
- [x] has an [appropriate license](https://github.com/sindresorhus/awesome/blob/master/awesome.md#choose-an-appropriate-license) *(Meaning something like CC0, NOT a code licence like MIT, BSD, Apache, etc)*,
- [x] has [contribution guidelines](https://github.com/sindresorhus/awesome/blob/master/awesome.md#include-contribution-guidelines),
- [x] has been checked for inconsistent formatting, spelling, and grammar *(This includes starting each link description with an uppercase character and ending it with a period `.`, and consistent naming)*,
- [x] has been added at the bottom of the appropriate category.

readme.md

@@ -103,6 +103,7 @@ Check out my [blog](https://blog.sindresorhus.com) and follow me on [Twitter](ht
 - [Elm](https://github.com/isRuslan/awesome-elm)
 - [Erlang](https://github.com/drobakowski/awesome-erlang)
 - [Julia](https://github.com/svaksha/Julia.jl)
+- [Liquid](https://github.com/simpyll/awesome-liquid)
 - [Lua](https://github.com/LewisJEllis/awesome-lua)
 - [C](https://github.com/aleksandar-todorovic/awesome-c)
 - [C/C++](https://github.com/fffaraz/awesome-cpp)