[docs] Add FAQ entry regarding forked repos + bump the bundler version. (#4078)

* [docs] Add FAQ entry regarding forked repos + bump the bundler version.

* format

docs/Gemfile.lock

@@ -245,4 +245,4 @@ DEPENDENCIES
   github-pages
 
 BUNDLED WITH
-   1.16.1
+   2.1.4

docs/faq.md

@@ -45,6 +45,13 @@ You should look for places in your code that:
   - look for existing fuzz target [examples](https://github.com/google/oss-fuzz/tree/master/projects)
     and find similarities.
 
+## Where can I store fuzz target sources and the build script if it's not yet accepted upstream?
+
+Fuzz target sources as well as the build script may temporarily live inside the
+`projects/<your_project>` directory in the OSS-Fuzz repository. Note that we do
+not accept integrations that rely on forked repositories. Refer to the
+[ideal integration guide] for the preferred long term solution.
+
 ## My project is not open source. Can I use OSS-Fuzz?
 
 You cannot use OSS-Fuzz, but you can use [ClusterFuzz] which OSS-Fuzz is based
@@ -152,6 +159,7 @@ possible. We believe that public code coverage reports do not put users at risk,
 as they do not indicate the presence of bugs or lack thereof.
 
 ## What happens when I rename a fuzz target ?
+
 If you rename your fuzz targets, the existing bugs for those targets will get
 closed and fuzzing will start from scratch from a fresh corpora
 (seed corpus only). Similar corpora will get accumulated over time depending on
@@ -163,14 +171,15 @@ restore it to the new GCS location later (instruction to find the
 new location [here]({{ site.baseurl }}/advanced-topics/corpora/#viewing-the-corpus-for-a-fuzz-target)).
 
 ## Does OSS-Fuzz support AFL or honggfuzz?
+
 OSS-Fuzz *uses* both [AFL](https://lcamtuf.coredump.cx/afl/) and
 [honggfuzz](https://github.com/google/honggfuzz)
 [fuzzing engines]({{ site.baseurl }}/reference/glossary/#fuzzing-engine).
-Follow the
-[ideal integration guide]({{ site.baseurl }}/advanced-topics/ideal-integration/)
-and OSS-Fuzz will use all its fuzzing engines on your code.
+Follow the [ideal integration guide] and OSS-Fuzz will use all its fuzzing
+engines on your code.
 
 ## What are the specs on your machines?
+
 OSS-Fuzz builders have 32CPU/28.8GB RAM.
 
 Fuzzing machines only have a single core and fuzz targets should not use more
@@ -184,3 +193,4 @@ corpora generated by OSS-Fuzz. OSS-Fuzz infrastructure is fully open source
 have no intent to restrict the use of the artifacts produced by OSS-Fuzz.
 
 [ClusterFuzz]: https://github.com/google/clusterfuzz
+[ideal integration guide]: {{ site.baseurl }}/advanced-topics/ideal-integration/