[Website] Fix dead links and references to /site directory (#4527)

Author: pdolif

site3/website/src/pages/bps/BP-35-128-bits-support.md

@@ -16,7 +16,7 @@ This BP proposes the changes for increasing ledger id from `63 bits` to `128 bit
 ### 128 bits
 
 Since there is no native support for `128 bits` in both Java and
-[Protobuf](https://github.com/google/protobuf/issues/2180), we have to break `128 bits`
+[Protobuf](https://github.com/protocolbuffers/protobuf/issues/2180), we have to break `128 bits`
 into 2 `64 bits` numbers for representing the `128 bits` id:
 
 - ledger-id-msb: the most significant 64 bits, bit 64 - 127

site3/website/src/pages/community/bookkeeper-proposals.md

@@ -45,9 +45,9 @@ Here is the process for making a BP:
 1. Write the proposal for this BP. There are two ways to write a bookkeeper proposal. You can choose to write a BP using markdown, or write a BP
 using Google Doc.
     - Markdown
-        - Make a copy of the [BP-Template](https://github.com/apache/bookkeeper/tree/master/site/bps/BP-template.md). Name the BP file as `BP-<number>-[caption-of-proposal].md`.
+        - Make a copy of the [BP-Template](https://github.com/apache/bookkeeper/tree/master/site3/website/src/pages/bps/BP-template.md). Name the BP file as `BP-<number>-[caption-of-proposal].md`.
         ```shell
-        $ cp site/bps/BP-template.md site/bps/BP-xyz-capation-of-proposal.md
+        $ cp site3/website/src/pages/bps/BP-template.md site3/website/src/pages/bps/BP-xyz-capation-of-proposal.md
         ```
         - Fill the sections listed in the BP template.
             - issue: replace `<issue-number>` with the issue number.
@@ -60,7 +60,7 @@ using Google Doc.
     - add `BP` label to this PR
     - attach the google doc link in the PR description if the BP is written in google doc
     - don't associate this PR with any release or milestone
-    - edit `site/community/bookkeeper-proposals.md`:
+    - edit `site3/website/src/pages/community/bookkeeper-proposals.md`:
         - bump the next bp number
         - add this BP to `Inprogress` section
 1. You can tag committers on this RP for reviewers, or start a `[DISCUSS]` thread on Apache mailing list. If you are sending an email, please make sure that the subject

site3/website/src/pages/community/coding-guide.md

@@ -68,7 +68,7 @@ Please log the _stack traces_ at **ERROR** level, but never at **INFO** level or
 
 * Names should be thought through from the point of view of the person using the config.
 * The default values should be thought as best value for people who runs the program without tuning parameters.
-* All configuration settings should be added to [default configuration file](https://github.com/apache/bookkeeper/blob/master/conf/bk_server.conf) and [documented](https://github.com/apache/bookkeeper/blob/master/site/_data/config/bk_server.yaml).
+* All configuration settings should be added to [default configuration file](https://github.com/apache/bookkeeper/blob/master/conf/bk_server.conf) and [documented](https://github.com/apache/bookkeeper/blob/master/site3/website/docs/reference/config.md).
 
 ### Concurrency
 

site3/website/src/pages/community/contributing.md

@@ -252,4 +252,4 @@ At some point in the review process, you should take the pull request over and c
 The BookKeeper website is in the same [BookKeeper Github Repo](https://github.com/apache/bookkeeper). The source files are hosted under `site` directory in `master` branch,
 the static content is generated by CI job and merged into the `asf-site` branch.
 
-Follow the [README](https://github.com/apache/bookkeeper/tree/master/site) for making contributions to the website.
+Follow the [README](https://github.com/apache/bookkeeper/tree/master/site3) for making contributions to the website.