Merge torrust#750: Minor fixes

fbd0469 fix: revert number of active UDP request to previous value (Jose Celano)
294357b docs: [torrust#746] add missing flamegraph in docs (Jose Celano)

Pull request description:

  Minor fixes.

  - Missing flamegraph image in docs.
  - Revert the number of active UDP requests to the original value (50). It was changed accidentally.

ACKs for top commit:
  josecelano:
    ACK fbd0469

Tree-SHA512: 5cbaf9f82dc58b5338b7659f0ecf909b2a08726a96676c9b2dda82cceafed9f5771ad7bc19e2b27c9553b74150dc8c32ff9e94293b33a91d203625e0854e2ebd

Author: josecelano

.gitignore

@@ -6,10 +6,10 @@
 /data.db
 /database.db
 /database.json.bz2
+/flamegraph.svg
 /storage/
 /target
 /tracker.*
 /tracker.toml
 callgrind.out
-flamegraph.svg
 perf.data*