runtime(doc): grammar fixes in doc (#13164)

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/ft_rust.txt b/runtime/doc/ft_rust.txt
index 9d5eb8c..fb8141c 100644
--- a/runtime/doc/ft_rust.txt
+++ b/runtime/doc/ft_rust.txt
@@ -474,8 +474,8 @@
 		register.
 
 :RustInfoToFile [filename]                                   *:RustInfoToFile*
-		Saves debugging info of the Vim Rust plugin to the the given
-		file, overwritting it.
+		Saves debugging info of the Vim Rust plugin to the given file,
+		overwriting it.
 
 ==============================================================================
 MAPPINGS                                                       *rust-mappings*
diff --git a/runtime/doc/terminal.txt b/runtime/doc/terminal.txt
index c02a885..62bc6e6 100644
--- a/runtime/doc/terminal.txt
+++ b/runtime/doc/terminal.txt
@@ -1532,7 +1532,7 @@
 argument that is the name of the pty.
 							*gdb-version*
 Only debuggers fully compatible with gdb will work.  Vim uses the GDB/MI
-interface.  The "new-ui" command  requires gdb version 7.12 or later.  if you
+interface.  The "new-ui" command requires gdb version 7.12 or later.  If you
 get this error:
 	Undefined command: "new-ui". Try "help".~
 Then your gdb is too old.
diff --git a/runtime/doc/version9.txt b/runtime/doc/version9.txt
index ee5b68d..09d6b3b 100644
--- a/runtime/doc/version9.txt
+++ b/runtime/doc/version9.txt
@@ -1198,7 +1198,7 @@
 Files:      src/evalwindow.c, src/testdir/test_getvar.vim
 
 Patch 8.2.0118
-Problem:    Crash when cycling to buffers involving popup window .
+Problem:    Crash when cycling to buffers involving popup window.
 Solution:   Do not decrement buffer reference count.
 Files:      src/popupwin.c, src/testdir/test_popupwin.vim,
             src/testdir/dumps/Test_popupwin_infopopup_7.dump