Fixed typo for PRIVATE-TOKEN header

Was PRIVATE_TOKEN but should be PRIVATE-TOKEN.
Underscore vs. kebab-case.

doc/api/builds.md

@@ -18,7 +18,7 @@ GET /projects/:id/builds
 ### Example of request
 
 ```
-curl -H "PRIVATE_TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v3/projects/1/builds"
+curl -H "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v3/projects/1/builds"
 ```
 
 ### Example of response
@@ -123,7 +123,7 @@ GET /projects/:id/repository/commits/:sha/builds
 ### Example of request
 
 ```
-curl -H "PRIVATE_TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v3/projects/1/repository/commits/0ff3ae198f8601a285adcf5c0fff204ee6fba5fd/builds"
+curl -H "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v3/projects/1/repository/commits/0ff3ae198f8601a285adcf5c0fff204ee6fba5fd/builds"
 ```
 
 ### Example of response
@@ -213,7 +213,7 @@ GET /projects/:id/builds/:build_id
 ### Example of request
 
 ```
-curl -H "PRIVATE_TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v3/projects/1/builds/8"
+curl -H "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v3/projects/1/builds/8"
 ```
 
 ### Example of response
@@ -277,7 +277,7 @@ POST /projects/:id/builds/:build_id/cancel
 ### Example of request
 
 ```
-curl -X POST -H "PRIVATE_TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v3/projects/1/builds/1/cancel"
+curl -X POST -H "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v3/projects/1/builds/1/cancel"
 ```
 
 ### Example of response
@@ -327,7 +327,7 @@ POST /projects/:id/builds/:build_id/retry
 ### Example of request
 
 ```
-curl -X POST -H "PRIVATE_TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v3/projects/1/builds/1/retry"
+curl -X POST -H "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v3/projects/1/builds/1/retry"
 ```
 
 ### Example of response