docs: fixed links on contributing.md not working from the main page (@Leonabcd123) (monkeytypegame#6982)

### Description

Used absolute paths instead of relative to make sure that the links in
the contributing.md file always work.

Closes monkeytypegame#6981 

Edit: just found monkeytypegame#6848 which seemed to try and do the same thing, they
just didn't get the right solution, because they still used relative
paths.

Author: Leonabcd123

docs/CONTRIBUTING.md

@@ -17,9 +17,9 @@ When contributing to Monkeytype, it's good to know our best practices, tips, and
 
 ## How to Contribute
 
-We have two separate contribution guides based on what you're looking to contribute. If you're simply looking to help us augment our language or quotes data, please refer to [CONTRIBUTING_BASIC.md](./CONTRIBUTING_BASIC.md). This guide will go over how to do so easily and without the need to set up a local development server.
+We have two separate contribution guides based on what you're looking to contribute. If you're simply looking to help us augment our language or quotes data, please refer to [CONTRIBUTING_BASIC.md](/docs/CONTRIBUTING_BASIC.md). This guide will go over how to do so easily and without the need to set up a local development server.
 
-If you're looking to make deeper code changes that affect functionality, or will require screenshots of the changes, please refer to [CONTRIBUTING_ADVANCED.md](./CONTRIBUTING_ADVANCED.md).
+If you're looking to make deeper code changes that affect functionality, or will require screenshots of the changes, please refer to [CONTRIBUTING_ADVANCED.md](/docs/CONTRIBUTING_ADVANCED.md).
 
 ## Standards and Guidelines
 
@@ -55,7 +55,7 @@ Before submitting a theme make sure...
 - your theme has been added to the `_list` file and the `textColor` property is the theme's main color
 - your theme is clear and readable with both `flip test colors` and `colorful mode` enabled and disabled
 
-If you want to contribute themes but don't know how, check [THEMES.md](./THEMES.md) 
+If you want to contribute themes but don't know how, check [THEMES.md](/docs/THEMES.md) 
 
 ### Language Guidelines
 
@@ -64,7 +64,7 @@ If you want to contribute themes but don't know how, check [THEMES.md](./THEMES.
 - Be sure to add your language to the `_list` and `_groups` files
 - Make sure the number of words in the file corresponds to the file name (for example: `languageName.json` is 200 words, `languageName_1k.json` is 1000 words, and so on)
 
-If you want to contribute languages but don't know how, check [LANGUAGES.md](./LANGUAGES.md)
+If you want to contribute languages but don't know how, check [LANGUAGES.md](/docs/LANGUAGES.md)
 
 ### Quote Guidelines
 
@@ -78,11 +78,11 @@ If you want to contribute languages but don't know how, check [LANGUAGES.md](./L
 - Remember to name your pull request properly. For example, if you are adding new quotes for the language `French`, your pull request should be named `impr(quotes): add French quotes`.
 
 
-If you want to contribute quotes but don't know how, check [QUOTES.md](./QUOTES.md)
+If you want to contribute quotes but don't know how, check [QUOTES.md](/docs/QUOTES.md)
 
 ### Layout Guidelines
 
-If you want to contribute layouts but don't know how, check [LAYOUTS.md](./LAYOUTS.md)
+If you want to contribute layouts but don't know how, check [LAYOUTS.md](/docs/LAYOUTS.md)
 
 ## Questions