docs(pull requests): rewrite (#21440)

Co-authored-by: Rhys Arkins <rhys@arkins.net>

docs/usage/key-concepts/pull-requests.md

@@ -7,23 +7,31 @@ This page describes how Renovate pull requests work.
 
 ## How Renovate finds existing PRs
 
-Renovate does not keep any kind of database/state of its own about open or closed Pull Requests.
+Renovate does not need to maintain any database/state about open or closed Pull Requests.
 Instead, it uses the code platform's APIs to search and find such PRs.
 
-Locating of existing PRs - whether open or closed - is done by matching both the branch name (e.g. `renovate/lodash-4.x`) and Pull Request title (e.g. `Update lodash to v4.17.21`).
+Renovate finds existing PRs (open or closed) by matching both:
 
-In cases like the above, there is typically at most one existing PR with the desired branch + title combination.
-When grouping is enabled by users, and PRs have titles like "All non-major updates", then there may be multiple past PRs which match.
+- the branch name, for example: `renovate/lodash-4.x`,
+- _and_ the Pull Request title, for example: `Update lodash to v4.17.21`
+
+In cases like the above, there is typically one existing PR with a matching branch name and PR title.
+But if you group PRs and use titles like "All non-major updates", then multiple past PRs may match.
 
 ## Normal PRs
 
-As described above, Renovate PRs normally have some uniqueness in their title relating to the version in the upgrade.
-In such cases, if a user closes such a PR, it can be inferred that they don't want to see it again in future.
-For example, they wish to ignore `lodash@4.17.21`.
+As explained above, Renovate PRs normally have some "uniqueness" in their title relating to the version in the upgrade.
+When you close a "unique" PR, Renovate assumes you don't want to see that PR again in future, for example:
+
+1. You ignored `lodash@4.17.21` by closing Renovate's PR
+1. Renovate assumes you don't want any updates to `4.17.21` of `lodash`
+1. Renovate creates a new PR when the branch + title "uniqueness" exists again, like when `lodash@4.17.22` releases
 
-In such cases, new PRs won't be created until the branch+title uniqueness exists again, such as if there is a `lodash@4.17.22`.
+Renovate behaves similarly for `major` updates, for example:
 
-Similarly in the case of major updates (such as "Update lodash to v4") then it can be inferred that the user wishes to ignore all of v4 of `lodash`, even when newer v4 versions are available.
+1. You ignored a `major` update for Lodash (pr title: "Update lodash to v4") by closing Renovate's PR
+1. Renovate assumes you don't want any updates to `v4` of `lodash`
+1. Renovate won't create any update PRs for `v4` of `lodash`, even if there are newer versions of `v4`
 
 ## Immortal PRs
 
@@ -62,7 +70,7 @@ Then the update becomes "Update react (major)", which is not safely ignorable, i
 ### Future plans for immortal PRs
 
 In the future we may embed metadata in each PR identifying the exact files and packages + versions that PR contains.
-Then we could allow such PRs to be closed/ignored but then as soon as there's any chance to files/packages/versions being updated then we'd be cached busted and create a new PR.
+Then we could allow such PRs to be closed/ignored but then as soon as there's any chance to files/packages/versions being updated then we'd be cache busted and create a new PR.
 If you regularly wish to close immortal PRs, it's an indication that you may be grouping too widely.
 
 ### How to fix immortal PRs