build fix

Author: norareidy

source/tutorial/commands.txt

@@ -103,7 +103,7 @@ Specifying a Custom Read Preference
 -----------------------------------
 
 Write commands, such as :manual:`createUser </reference/command/createUser>`,
-can only be executed on a writable server (e.g. :term:`primary` replica set
+can only be executed on a writable server (e.g. primary replica set
 member). Command helper methods in the |php-library|, such as
 :phpmethod:`MongoDB\Database::drop()`, know to apply their own :term:`read
 preference` if necessary. However, the :phpmethod:`MongoDB\Database::command()`