docs/DEPRECATE.md: grammar improvement and sp correction

The main thing I wanted to do was fix the spelling of "spent", but I
think this rewording improves the flow of the paragraph.

Closes #10067

docs/DEPRECATE.md

@@ -10,8 +10,8 @@ how your use case cannot be satisfied properly using a workaround.
 
 curl will *require* support for a 64 bit data type (like `long long` or an
 alternative) to build. These days, few systems are used where no such type is
-around so the cost of maintaining this support is increasingly unnecessary to
-spent effort and time on, while supporting 32 bit values for some of those
+around, so it is increasingly unnecessary to spend effort and time on
+maintaining this support. Also, supporting 32 bit values for some of those
 fields is complicated and hard to test.
 
 Adding this requirement will make the code simpler, easier to maintain and the