diff --git a/.spellcheck-en-custom.txt b/.spellcheck-en-custom.txt
index 22db77fb..bb9ae6f0 100644
--- a/.spellcheck-en-custom.txt
+++ b/.spellcheck-en-custom.txt
@@ -3,6 +3,8 @@
 Abhishek
 Akash
 AMDGPU
+API
+api
 arge
 arXiv
 backend
@@ -37,6 +39,7 @@ Eval
 Excalidraw
 exfiltrate
 exfiltrating
+extensibility
 Finetuning
 formedness
 GFX
@@ -135,3 +138,4 @@ XT
 XTX
 Xu
 YAML
+yaml
\ No newline at end of file
diff --git a/README.md b/README.md
index b03af186..f998a2a1 100644
--- a/README.md
+++ b/README.md
@@ -46,4 +46,4 @@ easily updated in the future as needed. Some options include:
 
 ### API Specifications
 
-API definitions use [OpenAPI](https://www.openapis.org/) format in [yaml](https://yaml.org/).
+API definitions use [OpenAPI](https://www.openapis.org/) format in [YAML](https://yaml.org/).
diff --git a/docs/api-definitions-guidelines.md b/docs/api-definitions-guidelines.md
index af8ecf7c..0dae2825 100644
--- a/docs/api-definitions-guidelines.md
+++ b/docs/api-definitions-guidelines.md
@@ -13,7 +13,7 @@ The `InstructLab APIs` are essential for hosting `InstructLab` as a service in a
 
 ## How will service APIs be defined?
 
-Service APIs will be defined using [OpenAPI](https://www.openapis.org/) format in [yaml](https://yaml.org/). For structural and style guidelines, see [api-definitions](../api-definitions/README.md).
+Service APIs will be defined using [OpenAPI](https://www.openapis.org/) format in [YAML](https://yaml.org/). For structural and style guidelines, see [api-definitions](../api-definitions/README.md).
 
 ## Where will service API definitions live?