docs: discuss caching personal access tokens

Documentation/git-credential-cache.txt

@@ -78,6 +78,23 @@ variable (this example increases the cache time to 1 hour):
 $ git config credential.helper 'cache --timeout=3600'
 -------------------------------------------------------
 
+PERSONAL ACCESS TOKENS
+----------------------
+
+Some remotes accept personal access tokens, which are randomly
+generated and hard to memorise. They typically have a lifetime of weeks
+or months.
+
+git-credential-cache is inherently unsuitable for persistent storage of
+personal access tokens. The credential will be forgotten after the cache
+timeout. Even if you configure a long timeout, credentials will be
+forgotten if the daemon dies.
+
+To avoid frequently regenerating personal access tokens, configure a
+credential helper with persistent storage. Alternatively, configure an
+OAuth credential helper to generate credentials automatically. See
+linkgit:gitcredentials[7], sections "Available helpers" and "OAuth".
+
 GIT
 ---
 Part of the linkgit:git[1] suite

Documentation/gitcredentials.txt

@@ -66,18 +66,7 @@ storage provided by the OS or other programs. Alternatively, a
 credential-generating helper might generate credentials for certain servers via
 some API.
 
-To use a helper, you must first select one to use. Git currently
-includes the following helpers:
-
-cache::
-
-	Cache credentials in memory for a short period of time. See
-	linkgit:git-credential-cache[1] for details.
-
-store::
-
-	Store credentials indefinitely on disk. See
-	linkgit:git-credential-store[1] for details.
+To use a helper, you must first select one to use (see below for a list).
 
 You may also have third-party helpers installed; search for
 `credential-*` in the output of `git help -a`, and consult the
@@ -106,6 +95,28 @@ $ git config --global credential.helper foo
 
 === Available helpers
 
+Git currently includes the following helpers:
+
+cache::
+
+    Cache credentials in memory for a short period of time. See
+    linkgit:git-credential-cache[1] for details.
+
+store::
+
+    Store credentials indefinitely on disk. See
+    linkgit:git-credential-store[1] for details.
+
+Popular helpers with secure persistent storage include:
+
+    - git-credential-libsecret (Linux)
+
+    - git-credential-osxkeychain (macOS)
+
+    - git-credential-wincred (Windows)
+
+    - https://github.com/git-ecosystem/git-credential-manager[Git Credential Manager] (cross platform, included in Git for Windows)
+
 The community maintains a comprehensive list of Git credential helpers at
 https://git-scm.com/doc/credential-helpers.
 
@@ -116,6 +127,12 @@ OAuth credential helper. Initial authentication opens a browser window to the
 host. Subsequent authentication happens in the background. Many popular Git
 hosts support OAuth.
 
+Popular helpers with OAuth support include:
+
+    - https://github.com/git-ecosystem/git-credential-manager[Git Credential Manager] (cross platform, included in Git for Windows)
+
+    - https://github.com/hickford/git-credential-oauth[git-credential-oauth] (cross platform, included in many Linux distributions)
+
 CREDENTIAL CONTEXTS
 -------------------