Update contribution.mdx (#3054)

* Update contribution.mdx

hotfix for doc-builder parsing quote in heading bug

* quoteation replace

docs/source/en/conceptual/contribution.mdx

@@ -170,7 +170,7 @@ please have a look at the next sections.
 
 For all of the following contributions, you will need to open a PR. It is explained in detail how to do so in the [Opening a pull requst](#how-to-open-a-pr) section.
 
-### 4. Fixing a "Good first issue"
+### 4. Fixing a `Good first issue`
 
 *Good first issues* are marked by the [Good first issue](https://github.com/huggingface/diffusers/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22) label. Usually, the issue already
 explains how a potential solution should look so that it is easier to fix.
@@ -275,7 +275,7 @@ Once an example script works, please make sure to add a comprehensive `README.md
 
 If you are contributing to the official training examples, please also make sure to add a test to [examples/test_examples.py](https://github.com/huggingface/diffusers/blob/main/examples/test_examples.py). This is not necessary for non-official training examples.
 
-### 8. Fixing a "Good second issue"
+### 8. Fixing a `Good second issue`
 
 *Good second issues* are marked by the [Good second issue](https://github.com/huggingface/diffusers/issues?q=is%3Aopen+is%3Aissue+label%3A%22Good+second+issue%22) label. Good second issues are
 usually more complicated to solve than [Good first issues](https://github.com/huggingface/diffusers/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22).