Update most URLs to docs.github.com (#1896)

Now that GitHub have moved their documentation from
developer.github.com, we should update our links. I have also tried to
update the call strings to their new format, but since it was done via
regex, some of them may not match exactly.

github/Project.py

@@ -28,7 +28,7 @@ from . import Consts
 
 class Project(github.GithubObject.CompletableGithubObject):
     """
-    This class represents Projects. The reference can be found here http://developer.github.com/v3/projects
+    This class represents Projects. The reference can be found here http://docs.github.com/en/rest/reference/projects
     """
 
     def __repr__(self):
@@ -140,7 +140,7 @@ class Project(github.GithubObject.CompletableGithubObject):
 
     def delete(self):
         """
-        :calls: `DELETE /projects/:project_id <https://developer.github.com/v3/projects/#delete-a-project>`_
+        :calls: `DELETE /projects/{project_id} <https://docs.github.com/en/rest/reference/projects#delete-a-project>`_
         :rtype: None
         """
         headers, data = self._requester.requestJsonAndCheck(
@@ -156,7 +156,7 @@ class Project(github.GithubObject.CompletableGithubObject):
         private=github.GithubObject.NotSet,
     ):
         """
-        :calls: `PATCH /projects/:project_id <https://developer.github.com/v3/projects/#update-a-project>`_
+        :calls: `PATCH /projects/{project_id} <https://docs.github.com/en/rest/reference/projects#update-a-project>`_
         :param name: string
         :param body: string
         :param state: string
@@ -194,7 +194,7 @@ class Project(github.GithubObject.CompletableGithubObject):
 
     def get_columns(self):
         """
-        :calls: `GET /projects/:project_id/columns <https://developer.github.com/v3/projects/columns/#list-project-columns>`_
+        :calls: `GET /projects/{project_id}/columns <https://docs.github.com/en/rest/reference/projects/columns#list-project-columns>`_
         :rtype: :class:`github.PaginatedList.PaginatedList` of :class:`github.ProjectColumn.ProjectColumn`
         """
 
@@ -208,7 +208,7 @@ class Project(github.GithubObject.CompletableGithubObject):
 
     def create_column(self, name):
         """
-        calls: `POST /projects/:project_id/columns <https://developer.github.com/v3/projects/columns/#create-a-project-column>`_
+        calls: `POST /projects/{project_id}/columns <https://docs.github.com/en/rest/reference/projects/columns#create-a-project-column>`_
         :param name: string
         """
         assert isinstance(name, str), name