DRIVERS-2789 Convert Server Write Commands Spec to Markdown

Author: blink1073

source/driver-bulk-update.rst

@@ -100,7 +100,7 @@ https://github.com/mongodb/mongo/blob/master/src/mongo/shell/bulk_api.js
 
 If you need more information about the actual write command you can find the specification at the following location
 
-https://github.com/mongodb/specifications/blob/master/source/server_write_commands.rst
+server_write_commands.md
 
 Modes of Execution
 ------------------

source/index.md

@@ -46,3 +46,4 @@
 - [URI Options Specification](uri-options/uri-options.md)
 - [Unified Test Format](unified-test-format/unified-test-format.md)
 - [Wire Compression in Drivers](compression/OP_COMPRESSED.md)
+- [Write Commands Specification](./server_write_commands.md)