doc: fix misspelling of “initialization” in diagnostics.html

initilization -> initialization

Change-Id: Ie5edd30559941f2d044280d8d586c2c2692d5b69
GitHub-Last-Rev: 7495a8c
GitHub-Pull-Request: #42749
Reviewed-on: https://go-review.googlesource.com/c/go/+/272026
Reviewed-by: Emmanuel Odeke <[email protected]>
Trust: Ian Lance Taylor <[email protected]>

Author: HollowMan6

doc/diagnostics.html

@@ -455,7 +455,7 @@ <h3 id="godebug">GODEBUG</h3>
 each collection, summarizing the amount of memory collected
 and the length of the pause.</li>
 <li>GODEBUG=inittrace=1 prints a summary of execution time and memory allocation
-information for completed package initilization work.</li>
+information for completed package initialization work.</li>
 <li>GODEBUG=schedtrace=X prints scheduling events every X milliseconds.</li>
 </ul>